House Democrats are expected to approve today the outlines of a legislative alternative to President Reagan's trade policy that would penalize foreign nations that restrict American products and require greater intervention in international currency markets to bring down the value of the dollar.

The resolution, which will be brought before the House Democratic Caucus with strong leadership support, puts the trade action on a legislative fast track in an effort to jump ahead of the White House and congressional Republicans, who are trying to fashion trade positions of their own.

The resolution calls for House committees to approve the elements of a comprehensive trade bill by Oct. 30 so it can come up for a floor vote by the end of the year.

According to the resolution, made available yesterday to The Washington Post, the Democratic program offers broad outlines of a trade policy with the details left to the House committees with overlapping jurisdiction.

It would require aggressive promotion of American exports, including low-cost financing to counter subsidized interest rates offered by countries such as France and Japan. The administration appears likely to support a similar program, although over the past five years the White House has fought congressional efforts to strengthen the Export-Import Bank and once called for its abolition.

Other parts of the Democratic initiative would strengthen laws to deal with unfair trade practices and end barriers to American products in overseas markets, and increase domestic programs to help U.S. companies and workers who have been hurt by record trade deficits, expected to reach $150 billion this year.

The resolution calls for legislation closely resembling a bill with strong House support that the president has denounced as a protectionist measure. Sponsored by Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.), Rep. Richard A. Gephardt (D-Mo.) and Sen. Lloyd Bentsen (D-Tex.), the bill would force nations with large trade surpluses to open their markets to American products or face a 25 percent import surcharge.

Its sponsors deny the bill is protectionist, describing it instead as a market-expanding measure.

The initiative, sponsored by Rep. Stan Lundine (D-N.Y.), won the endorsement of a special task force on trade named by Majority Leader Jim Wright (D-Tex.). Rep. Don Bonker (D-Wash.), who heads the task force, said he expects the resolution will get overwhelming support from the Democratic caucus.

"Based on what I hear from members in the cloak room, trade is the number one issue," said House Speaker Thomas P. (Tip) O'Neill.

President Reagan, meanwhile, continued his attack on those bills during an appearance in Concord, N.H., that was supposed to be devoted to tax overhaul.

"What we can't do is be stampeded into the dark hole of protectionism, igniting a trade war that will undercut everything we've accomplished and, in the long run, throw millions of Americans out of work," Reagan said in an echo of his comments on trade during his press conference Tuesday night.

Despite record trade deficits, the president asserted, "There is reason for optimism on the trade front." He cited greater efficiency in U.S. industry, "a jump in worker productivity" and increased investments in new technology brought about by "our tax rate reductions."

"This is the way to a more competitive America and lasting progress," Reagan said.

But congressional Democrats castigated Reagan for his press conference remarks on trade, which Sen. Max Baucus (D-Mont.) said "demonstrated an unbelievable lack of knowledge and concern about our international trade situation."

"When the president of the United States denies that we are a debtor nation two days after his Commerce Department announces that we are, that is cause for concern," added Bentsen.

Bentsen said Reagan's comments that trade deficits aren't important since the United States ran them most of the last century "demonstrates only that he doesn't comprehend the difference between a developing nation and a world economic power."

Lundine attacked Reagan as "a president who is willing to commit troops in Central America and to put nuclear weapons in space, yet he refuses to take actions to force our trading partners to open their markets to U.S. goods, stop their unfair trading practices, and come to some reasonable accommodation on the grossly inflated value of the U.S. dollar."

Senate Minority Leader Robert C. Byrd (D-W.Va.) defended protectionism "as not to bad a word" if it used "to protect American jobs, American workers and American industries."