Howard University went to its dunk offense late in the first half against pesky Jackson State and went on to its third straight victory, 81-70, before 2,700 fans last night at Burr Gymnasium.

Unbeaten Howard trailed the perimeter-shooting Tigers, 29-28, before James Ratiff (25 points) ignited a 22-6 blitz that gave the Bison a 50-35 half-time lead.

The 6-foot-8 Ratiff started the spurt with a dunk off a perfect lob pass from Rodney Wright. Ratiff was fouled on the play and converted the free throw to give Howard a 31-29 lead. Larry Spriggs, playing his first game after injuring his ankle during the preseason, followed with a flying one-handed dunk.

Ratiff then threw in seven more points and Spriggs (18) and James Terry (15) added four points each in the blitz.

While Howard was frolicking its way to its best first half of its young season, Jackson State was having no luck either getting the ball inside or preventing the Bison from dominating the boards.

"Our big kid (6-10 Audie Norris) was hurt and we're not a very good team without him," said Tiger Coach Paul Covington. "Howard is a very good rebounding team and we allowed them to get the offensive board in the first half.

"We stopped playing with our heads and started playing with our hands and feet. We threw up some bad shots," said Covington. "They forced us to play outside."

Norris entered in the second half and controlled the Bison big men enough to keep the score close. The sophomore scored 15 points and grabbed four rebounds in the final 20 minutes, but JSU could get no closer than nine points.

Jump shots by Ricky Hill and Northern Shavers pulled the Tigers to 68-59 with 5:10 left; Howard had lost its first-half sharpness and had grown erratic.

"You know how you can get that early lead on a team and come out the second half and relax," said Wright, who finished with eight points, eight assists and seven rebounds. "We played helter-skelter and made a few mistakes. Larry (Spriggs) gave us a big boost. And Ratiff played real well."

Jackson State had three chances to further reduce the deficit but botched two fast-break opportunities and lost the ball on a turnover. Although the Bison failed to score after each break, they still led by nine points with about four minutes left.

Having seen enough, Howard Coach A. B. Williamson went back to his starting front line. Bison guard Louis Wilson slipped down the lane for a layup, Spriggs was given credit for a basket on a goaltending call against Norris and Ratiff fired a perfect length-of-the-court pass to a streaking Wilson for a breakaway to put Howard up, 74-59.

Williamson, whose club faces '78-79 NIT quarterfinalist Alcorn State at Burr Monday night, was pleased with his team's play in the first half.

"We showed a lot of poise and consistency in the first half," said Williamson. "We let up some the second half. We had some trouble with their press. It's early in the year and we have some work to do. We knew how to start to break the press but we didn't know how to finish."

Howard controlled the inside and Jackson State pumped from the outside in the game's opening 12 minutes as the lead seesawed. Shavers (19) dropped in one of two free throws to give the Tigers their final lead at 29-28.

Howard shot 58 percent for the game (36 of 62) and won the backboard war, 53-34. Jackson State was only 31 of 81 from the floor.