The political arm of Maryland's labor movement has a computer band filled with 350,000 names, each representing a potential volunteer in the campaign for governor. It has access to thousands of dollars for campaign contributions and a sophisticated mailing list that any candidate might envy.

This week, the state's AFL-CIO Committee on Political Education will bestow these gifts on the man who can win two-thirds of the vote at its special convention.

So on Saturday night, Acting Gov. Blair Lee II invited some 40 labor leaders to dine on the state yacht,"The Maryland Lady," and to be told of his strategy for winning labor's endorsement - or at least keeping his rival Theodore G. Venetoulis from receiving it.

Lee, his running mate Steny Hoyer and his compaign director Fran Tracey gave the labor leaders at least two reasons for endorsing the Lee-Hoyer ticket. Lee is ahead in the polls, they said, and the withdrawal of Attorney General Franicis B. Burch from the race should add to Lee's edge.

"They said we should go for no endorsement, if Lee could not receive it, because labor should not chose between two of its good friends - Lee and Venetoulis," said a labor leader who attended the party but asked not to be identified.

That labor official,who supports Lee, thought the evening a success. "It bolstered the Lee supporters in labor," he said. "A lot of people were concerned that Lee wasn't making an effort."

Venetoulis, on the other hand, has been courting labor, picking up the asyet-unannounced endorsement of the American Federation of State, County and Municipal Employees, recommendations for endorsement from the Baltimore area and Washington area labor councils and the endorsement of the black trade unionist group in Maryland.

Until the yacht party, paid for by the Lee-Hoyer campaign, Ventoulis was confident he would win the COPE endorsement. Now, according to his campaign manager, Jackie Smelkinson, there is concern over Lee's attempts to block any endorsement.

"Ted's been doing his homework for four years, his record shows it, and I'd hate to see the yacht party hold up the endorsement," Smelkinson said. "It's another eleventh-hour meeting like Lee tried with the teachers."

Venetoulis won the endorsement of the Maryland Education Association early this summer, reaping the benefit of the help of volunteers from the 35,000-member group. Just before the teachers' convention, Lee substantially modified his previous stand in support of a state pension reform bill that the teachers had vehemently opposed.

With only six weeks remaining until the Sept. 12 primary, the labor endorsement is taking on far greater importance than it had in the last gubernatorial campaign. In the 1974 election, COPE remained neutral, refusing to endorse the Marvin Mandel-Blair Lee ticket because of labor's bitterness over Mandel's handling of a police stride in Baltimore. Mandel greatest margin in the state's history, and Lee nevertheless won by the state's history.

But political observes are pointing to the 1976 Democratic primary for the U.S. Senate as the reason for the intense interest in labor this year. Labor's endorsement of Paul S. Sarbanes over Joseph D. Tydings was credited with giving Sarbanes an upset victory that carried him to election.

The statewide labor endorsement is more crucial to Venetoulis than to Lee, who has picked up some broad-based support from elected officials and Democratic clubs around the state. Venetoulis received the AFL-CIO endorsement in his 1974 race for Baltimore County executive. While in that office he maintained a record favorable to labor, according to COPE officials.

"It was in big and small ways," a state labor leader who favors Lee explained. "For instance, when there was a strike at the Sheraton-Lanham hotel recently, Hoyer crossed the picket lines several times, I think once for a meeting with Mandel. Venetoulis wouldn't. He told the strikers he would go inside and get the friend he was meeting to eith him to other restaurant."

Hoyer, however, has maintained the same kind of pro-lanor legislative record that Venetoulis has. In his last four years as president of the State Senate, Hoyer received a 96 percent favorbale rating from labor groups.

Lee's record, accroding to COPE officials, has not been as good.