Maryland legislators, in the midst of grappling with a loss of federal unemployment benefits, will receive the gloomy news tomorrow that another 180,000 of the state's workers lost their jobs in June.

Maryland's unemployment rate rose from 8.6 percent in May to 9 percent a month later, according to Human Resources Secretary Kalman R. Hettleman. The increase, due largely to seasonal layoffs, underscores the persistent unemployment crisis that has gripped the state for most of the year. In January, nearly 10 percent of the state's 2 million workers were without jobs, the highest level since World War II.

The new unemployment figures, to be released tomorrow, come as the 188-member General Assembly prepares for a special legislative session Friday to consider additional state aid to 11,000 workers whose federal unemployment benefits expired on Aug. 1. The federal cuts affect workers who have been without jobs for more than 26 weeks and who, until the federal guidelines were changed a year ago, would have been eligible for federal checks for an additional 13 weeks.

(The Reagan administration said yesterday it is considering restoring the extra 13 weeks' benefits and easing even tougher requirements scheduled to take effect next month.)

Gov. Harry Hughes, a Democrat seeking reelection, called the special legislative session last week after an outcry from the state's politically powerful labor unions. The measure he has proposed will provide $8 million to $9 million in state funds to offset the loss in federal benefits and also will relax the formula for calculating benefits.

Since Hughes announced plans for a special session, there has been virtually no opposition to the idea, and that was again the case today when the Maryland House and Senate committees held a joint hearing on the proposed legislation.

Speaking in favor of the legislation were Republican and Democratic legislators, representatives of the state Chamber of Commerce, leaders of the state AFL-CIO and Republican gubernatorial candidate Robert A. Pascal. The state's ongoing gubernatorial campaign was evident several times during the hearing.

"People are out there hurting. This bill should be passed," said Pascal, who earlier in the day held a press conference to announce his own plans for retraining laid-off workers.

Pascal made sure he was included in the first group of speakers at the hearing, which drew most of the newspaper and television reporters from Washington and Baltimore. He testified for less than a minute.

Baltimore Sen. Harry J. McGuirk, who is challenging Hughes in the Sept. 14 Democratic primary, used his prerogative as chairman of the meeting to give a gentle poke at Hughes's economic policies. When Human Resources Secretary Hettleman made a passing reference to the administration's accomplishments in economic development, McGuirk retorted, "Would you tell us what they are please, Mr. Hettleman, because if they are so active I'd like to know why we have so much unemployment?"

Hughes' chief of staff, Ejner Johnson, answered that federal economic policies were the controlling factor in unemployment, but McGuirk's comment provoked a chuckle from Pascal, who was sitting in the audience.

Maryland's benefits crisis resulted from a change in federal unemployment formulas that went into effect last August. These changes, which the Reagan administration pushed as a cost-saving measure, calculate a state's unemployment level by considering only those who most recently lost their jobs.

Under those guidelines, a state receives federal unemployment funds only if at least 4 percent of its covered workers--excluding those who have been unemployed for six months or more--are out of work. On July 10, that rate in Maryland dipped to 3.96 percent, making the state ineligible for further federal benefits.

Maryland legislators said they knew that the still stricter federal guidelines scheduled to go into effect Sept. 26, which sets the "trigger" for federal benefits at 5 percent, would result in a loss of federal funds, so they voted state funds during the regular session last winter to make up for that expected loss. State officials said that Maryland would have to be in a depression to qualify for federal unemployment funds after Sept. 26.

But state officials did not expect the cutoff of federal funds last month that occurred because of an apparent leveling off of the economy that resulted in a reduction in the number of workers recently laid off.