The first public opposition to a tax-cutting TRIM proposal in Prince George's County surfaced yesterday when two lawyers who represent serveral apartment owners in the county filed suit to remove the refendum from the November ballot.

Hyattsville attorneys Stanley S. Pickett and R. Calvert Steuart challenged the referendum, which is expected to win by an overwhelming margin, because they believe it is the first step toward a county "tier tax." with apartments and commercial buildinf being taxed at a higher level than single-family homes.

Steuart said he and Pickett filed the suit on their own after "gathering a lot of negative comments about the referendum" from the clients in the apartment and business fields. He noted that Pickett is himself the owner of an apartment house, Fernwood Terrace in Riverdale.

The TRIM referendum, which would breeze the county's total property tax levy at the amount raised for the 1979 budget, about $140 million, has been endorsed by virtually every political candidate and special interest group in the county, including County Executive Winfi eld M. kelly Jr. and his Republican opponent, Lawerence J. Hogan.

According to Steuart, apartment owners and businessmen have only recently realized that a little-publicized section of the referendum would adversely effect their tax posture. This section says that if state and county laws were passed to create a "tier tax" structure, only the owners of single-family homes would benefit from the property tax freeze - and this benefit would come at the expense of commercial properties.

"The referendum doesn't create the tier tax, but it opens the door and takes the first step," said Steuart. "We decided to fight that first step."

Steuart said that he and Pickett found two area in which they could challenge the constitutionality of the tax-cutting referendum after "starting with the premise that we didn't like the thing."

Their suit charges that the measure sponsored by TRIM (Tax Relief Initialtive by Marylanders) is unconstitutional because it strips the county of the unlimited taxing authority that is pledged in contracts with general revenue bond-holders.

It also contends that the referendum petitions were invalid because they failed to list the signers by precinct, district and ward, as required by state law.

County Attorney James C. Chapin, who will defend the referendum in court, said he believed the petitions were valid because they listed the signers by street address. "That is usually considered sufficient," he said. He noted that the bond obligation argument was used unsucessfully by those who challenged the Proposition 13 tax measure in California.

"We haven't really had time yet to research the suit," said Chapin. "But it looks as though the arguments have all been heard in the courts before."

The fact that business interests would challenge the Prince George's measure indicates how different it is from a referendum using the TRIM acronym in neighboring Montgomery COIunty, and from California's tax-cutting proposition 13.

The California and Montgomery County measures have been supported for the most part by more conservative business groups and opposed by labor unions and progressive social service organizations.

By contrast, the Prince George's referendum was conceived by two liberal Democrats - David Bird and William Goodman - whose goal was to force a greater reliance on a "tier tax" and income tax.

Steuart argued yesterday that a "tier tax" would actually hurt most the county's poorest residents - apartment renters. "If this forces apartment owners to pay more, they're just going to hit the renters for the money," said Steuart. "It's an open invitation to tax the hell out of apartment units."

Steuart and Picketts will appear before Circuit Court Judge George W. Bowling in Upper Marlboro on Nov. 3 to request a temporary restraining order to keep the referendum off the Nov. 7 ballots.