Negotiators for the National Football League and the striking NFL Players Association reached agreement today on a settlement of the 57-day-old strike, longest in professional sports in the nation's history.

Before midnight, the 28 player representatives had voted to accept the agreement and send it on for a vote of the full union membership. Their seven-member executive committee had passed on the agreement without making a recommendation.

The final step in player ratification is a majority vote of the NFLPA's 1,500 rank and file members, who will vote by secret ballot next Tuesday. Even before the ratification vote, however, plans are being made to play a full schedule of games Sunday after an absence of eight weeks.

Ed Garvey, executive director of the NFLPA said, "We'll have football on Sunday." He said the union will urge players to report to practice as soon as possible to prepare for Sunday's games.

The settlement also has been approved by the owners' management council. Now needed is a vote of approval by three-quarters of the league's 28 owners.

The Washington Redskins' first poststrike game will be with the New York Giants in East Rutherford, N.J. NFL practice was expected to begin Wednesday, although some members of the San Francisco 49ers worked out late today.

Jack Donlan, executive director of the NFL Management Council, the league's labor negotiating arm, confirmed that a tentative agreement had been reached early tonight after 11 hours of negotiations under the direction of Paul Martha, a Pittsburgh lawyer who was asked by Garvey to serve as an intermediary in settling the dispute.

Donlan said he was "pleased and elated" by the agreement and hoped for a speedy ratification. Donlan had said earlier that he hoped play could resume Sunday and that the Super Bowl could be played as scheduled in Pasadena, Calif., Jan. 30.

The new regular season would consist of nine games: the two played before the strike began, the six remaining and one game made up of the eight missed during the strike. Each team will play at least four of its nine remaining games at home. The nine-game season will be the shortest in the NFL's 63 years.

There will be a 16-team playoff, with eight teams qualifying from each of the two conferences. Normally, 10 teams make the playoffs. Under the revised format, eight games -- four in each conference -- will be played the weekend of Jan. 8-9, with the winners playing the weekend of Jan. 15-16.

The conference championships leading to the Super Bowl will be played the weekend of Jan. 22-23. Teams will qualify for the playoffs on their overall records.

Terms of the tentative pact were $1.28 billion in player costs over a four-year period beginning with the 1983 season plus $60 million in bonuses of up to $60,000 per player this year.

Additionally, players will be eligible for severance pay upon retirement after a minimum of four years in the league. The severance pay would start at $60,000 and increase at the rate of $10,000 a year for each additional year.

The agreement also includes a wage scale that begins at $30,000 a year for rookies. But it is substantially less than the $60,000 minimum for rookies sought by the union. What the union failed to win in the settlement was a percentage of TV revenues, creation of a trust fund from which player salaries would be drawn and its concept of a wage scale that would account for the major share of players' salaries.

Under terms of the agreement tentatively approved tonight, individual negotiations still would account for the major share of players salaries.

"We did not get everything we wanted. Management did not get everything they wanted," said Garvey, who nevertheless termed the strike a success. Garvey said he felt establishment of the wage scale was "a major step forward."

It was learned that the union's executive committee was unhappy over the fact that the proposed settlement failed to include bonuses for onfield performance. Additionally, the union members were said to be seeking two game checks for games not played because of the strike.

Eight weekends of games were called off because of the strike and two weekends were played before the strike was called on Sept. 20.

The tentative agreement came after 11 hours of negotiating at the St. Regis Hotel in midtown Manhattan under the auspices of Martha, a former Pittsburgh Steeler player who entered the discussion Saturday at Garvey's request.

Garvey invited Martha to enter the talks after he learned that the National Labor Relations Board had decided not to ask a federal court for an injunction to compel the NFL to begin bargaining in "good faith" with the union immediately. A complaint, issued in the name of the NLRB's general counsel, is pending against the NFL accusing the league of bad faith bargaining; a hearing on that charge had been scheduled for Nov. 29 in New York.

The decision not to seek the injunction, which would have expedited the process against the league, came as a significant blow to the union cause.

As part of the tentative settlement it was learned the union has agreed not to press the case further before the NLRB.

Participating in the talks on management's side, in addition to Donlan, were Chuck Sullivan, chairman of the management council's executive committee and the executive vice president of the New England Patriots, and Dan Rooney, president of the Pittsburgh Steelers, who also played a roll in negotiating a settlement of the 1974 NFL preseason strike.

Rooney was said to have been persuasive in obtaining an agreement from the league to provide current year bonuses for Herb Orvis of the Baltimore Colts and Mike Kadish of the Buffalo Bills, two union player representatives who were cut during the NFL's preseason. The union contended they were cut because of their union activity.

Martha, who is also vice president and general counsel of the Pittsburgh Penguins of the National Hockey League, met alternately today in separate meetings and joint sessions with the two sides. His entrance into the talks Saturday followed a one-week recess called Nov. 6 by Sam Kagel, a San Francisco attorney who tried unsuccessfully for eight days in New York and earlier for 12 days in Cockeysville, Md., to mediate a settlement of the dispute.

Today's agreement came as league negotiators were warning union counterparts that games could not be played Sunday unless there was a settlement today, and that unless games were played Sunday the season probably was over.