House Democrats were badly battered Tuesday, losing several powerful senior members, apparently including Ways and Means Committee Chairman Al Ullman (D-Ore.). But they held their majority, which provides the party the only national forum it will control next year.

With the White House and Senate lost of Republicans, the House will become the national Democratic Party to the extent that it exists as a combat force, and Speaker Thomas P. (Tip) O'Neill Jr. will be its leader.

But there may not be much to lead unless the shrunken Democratic forces display a sense of party discipline not seen recently. An already conservative House should become more so with the biggest Republican gains since their 1966 recovery from the 1964 anti-Goldwater landslide.

Republicans needed to pick up 59 seats in the 435-member House to gain control for the first time in a quarter century. They has gained 33 with about half a dozen still in doubt. This would leave a Democrats with a majority of about 25. But Democrats can expect more defections than this on any controversial issue. The Democrats majority thus probably won't provide much more than a block against some of President Reagan's proposals that Democrats find especially outrageous.

The most unusual aspect of the election was unusual aspect of the election was the number of powerful senior Democrats, including some party leaders and committee chairmen, who went down to defeat. Usually, it is the juniors who haven't had time to become entrenched who get blown away first in a bad year.

But the first incumbent Democrat to acknowledge defeat Tuesday evening was John Brademas (D-Ind.), a 22-year House member and third-ranking party leader as majority whip. Voters in South Bend apparently held him responsible as a leader for their unemployment problems.

Ways and Means Chairman Ullman was 2,000 or so votes down with several thousand absentee ballots to be counted. Democratic observers here expected him to lose. Ullman, a 24-year House member, had been considered vulnerable as a Washington-bound committee chairman who had become out of touch his district. He had sold his home in Oregon and though he hustled to buy a condominium when he realized his problems, that wasn't enough. Denny Smith, the apparent Republican winner, owns a chain of newspapers. An anti-nuclear third candidate in the race siphoned off 10,000 votes.

Ullman's likeliest successor as chairman of tax-writing Ways and Means is Rep. Dan Rostenkowski (D-Ill.), though he might choose instead to move up to succeed Brademas.

In eastern Washington, House Agriculture Committee Chairman Thomas Foley won a close race. But in northern California, House Public Works Committee Chairman Harold (Bizz) Johnson (D-Calif.) lost, apparently to age. (He is 72.) And in Los Angeles, Rep. James Corman (D-Calif.) -- chairman of the House welfare subcommittee plus the Democratic congressional campaign committee which handed out money to help other Democrats win their races -- lost to Bobbi Fielder, an anti-busing Los Angeles schol board member.

There was some grumbling among West Coast Democrats that President Carter's early concession statement an hour before the polls closed there might have caused some late voters in California to stay home who might other-wise have hurried out to vote for Carter and such candidates as Corman. Corman lost by only 800 votes.

Assuming House Democrats follow seniority, Johnson will be succeeded as chairman of the Public Works Committee by Rep. James Howard (D-N.J.), who was thought vulnerable himself because as chairman of the surface transportation subcommittee he hadn't improved the decrepit rail line many of his constituents use to commute to New York.

All told, there will be 74 new faces in the House.

Majority Leader Jim Wright (D-Tex.) and Interior Committee Chairman Morris K. Udall (D-Ariz.), both of whom where once thought to be in tough races, won easily. But a long list of important subcommittee chairmen were defeated. Included was Rep. Thomas (Lud) Ashley (D-Ohio), the House's Democratic housing expert and the savvy legislator whom O'Neill called on to guide the omnibus energy bill through the House in 1977.

Also defeated were Rep. Bob Eckhardt, Texas liberal and target of big oil; Lester Wolff (D-N.Y.), chairman of the Foreign Affairs subcommittee on Asia, criticized by his opponent for taking too many foreign trips; Lionel Van Deerlin (D-Calif.), subcommittee chairman who had taken on the task of updating the nation's basic communications law; Mike McCormack (D-Wash.), the leading House champion of nuclear power; and Rep. Rechardson Preyer (D-N.C.), highly respected former federal judge often called on by the leadership to chair efforts to toughen the House ethical code, who may have been considered too much a national Democrat for Greensboro.

The voters even took the unusual step of dumping a chairman of an Apropriations subcommittee when they threw out Rep. Gunn McKay(D-Utah), a 10-year member who chairs the military construction subcommittee. All these seniors had seen their majorities whittled down over the years and the combination of today's burdens was enough to unseat them.

Only one member caught in the FBI's Abscam web -- Rep. Raymond Lederer (D-Pa.) -- was reelected. Two House seniors under indictment on Abscam bribery charges -- Reps. Frank Thompson (D-N.J.) and John Murphy (D-N.Y.) -- were defeated. Two others convicted on Abscam charges -- Rep. John Jenrette (D-S.C.) and expelled former representative Michael Myers (D-Pa.) -- were denied reelection.

Women members in the House added a net of three, bringing their total to 19. Democrat Elizebeth Holtzman (D-N.Y.) left the House to run a losing race for the Senate. The four new women members are all Republicans. lState Sen. Lynn Martin of Rockford, Ill. took the place of John B. Anderson, who quit to run for President. Claudine Schneider, a former TV talk show host, defeated Democratic incombent Edward Beard in Rhode Island. Marge Roukema beat three-term Rep. Andrew Maguire (D-N.J.) and Fielder best Corman, a 20-year veteran.

The Black Caucus added a net of two, bringing its number of voting members to 16, all Democrats. Two non-voting delegates meet with them. The two blacks who will take over open white seats are former Lt. Gov. Mervyn Dymally in Los Angeles and Gus Savage, a newspaper editor in Chicago.

The only write-in winner was Republican Joe Skeen in New Mexico, After Rep. Harold Runnels (D) died last summer when he had no Republican opposition, Skeen was ruled too late to be placed on the printed ballot. So he tried a difficult write-in campaign and won.

The remarkable class of 1974 -- the big group of Democrats, many without previous political experience, elected after the Watergate scandal that forced President Nixon out of office -- lost some members but again displayed unusual staying powers. Until yesterday only seven of that group had been defeated in two subsequent elections, a departure from the usual rule that the pendulum swings back on election after a landslide to return seats to their traditional parties.

Fifty-six of the 75 Democrats first elected in 1974 ran for reelection Tuesday. It appeared that nine were defeated. But that ment 47 had been elected for a fourth time, many from districts that had long been Republican.

Other Democratic incumbents defeated Tuesday included Reps. Bill Burlison (Mo.), Lamar Gudger (N.C.), Jerome Amtro (N.Y.) Peter Kostmayer (Pa.), Alvin Baldus (Wis.), John Hutchinson (W.Va.), Rapheal Musto (Pa.), Bob Carr (Mich.), Jim Lloyd (Calif.), Herbert Harris (Va.) and Joseph Fisher (Va.)

Republicans lost 11-term Rep. Samuel Devine (Ohio), first-term Rep. Bill Royer (Calif.) and third-term Rep. Robert Bauman (Md.), who seemed wellembarked on a career as conservative leader until he was charged with soliciting sex from a teen-aged boy.