Marion Barry went before the D.C. Democratic State Committee last week and told the members that he is not only the mayor of the city, but plans to be the leader of the Democratic party as well.

Gone, he indicated, are the days of phantom politics in the mayor's office. Those were the days when Walter E. Washington was afraid to become too political for fear of what Congress would say, and didn't come to state committee meetings because most of its menbers supported his political opponents.

"In most cities or states, the highest elected official locally is active and ought to be active in party politics. That's the way it ought to be," Barry told the committee. "I'm gonna be active."

Talking to a reporter a day earlier, Barry was even clearer on what role he intends to play in city politics. "In most states or cities, the governor, or the mayor or the top elected official is the titular head or the real head of the party," Barry said. "I intend to be both."

Barry was making his first appearance as mayor before the committee, which was once bitterly divided over his candidacy for the party's mayoral nomination.Smiling committee members seemed visibly excited and delighted to be in the presence of the chief executive.

Barry met with the committee on serious political business. The new mayor is putting together a political machine-uh, organization-in this city, and having control of the state committee, the policy-making arm of the local Democratic party, is part of the process.

The mayor was talking no-nonsense politics, at times speaking very boldly.

"I don't feel the same way some of y'all do about the Hatch Act," Barry said of the federal law prohibiting partisan political activity by city employes. "I'm not gonna be a strict conformist . . . I'm gonna urge all the District of Columbia employes to participate in party politics."

Barry has staked out a bold political game plan. He needs an organization to solidify his power, and neither the Hatch Act, criticism of his appointment of alleged cronies or even the state committee is going to get in his way.

Already, campaign aides and past associates are getting key appointments in both the administration and on city boards and commission.

The mayor is planning to establish a new political base in Ward 7, the mostly black Far Northeast and Far Southeast section of the city. He may even buy a house there to solidify his support.

Barry seemed to be telling the state committee that-with him as mayor-the Democratic party will be going places. But it will undoubtedly be going where Barry wants it to go. Next year, when 44 seats on the committee are up for grabs, Barry said, he plans to take part in forming a slate of people who he thinks should fill thsoe seats.

The new mayor is not one to hold grudges with someone he may need later. Barry voiced support for committee chairman Robert B. Washington Jr., a lawyer who opposed Barry's campaign for the party's nomination for mayor. Some of Barry's supporters think Washington should go.

"Bob Washington and I have our differences from time to time.But I think he's been a good chairman," Barry said. Washington is up for reelection next month.

Barry also promised the 40 committee members that they would be asked to submit names for appointments by the mayor to city boards, commissions and administrative positions.

Barry told the committee he is in favor of the city having the authority to choose its own judges and prosecute its own criminal cases. "If we get these areas, we'll see a change at how the criminal justice system is advocated in this city," Barry said.

What he did not say was that there would also be increased patronage for local officials-the kind of patronage that helps build a strong political machine.

Barry now has a stock answer to the question of how can he assume such a political posture when he cried 'Foul' so loudly two years to Del. Walter E. Fauntroy's political efforts. Fauntroy was trying to keep Barry out of the race for mayor in order to increase the likelihood of former City Council chairman Sterling Tucker winning the nomination. Barry then likened his campaign to open defiance of the "political bosses."

"A machine implies sort of a dictatoria operation, you have a czar, a monarch who dictates to the troops," Barry explained to a reporter. "An organization is an operational way of getting things done. It's a two-way exchange . . . I criticized Walter Fauntroy for saying that I should not run."

The last few minutes of the state committee meeting were Barry's chance to hold court, to allow the state committee members to pay homage to the new king. Mr. Mayor was thanked by a teacher for intervening in the school strike. He was thanked by a clean-city advocate for vetoing a proposal to allow advertising on taxicabs.He was thanked for a donation to the committee of $6,000 from his campaign organization.

Then Barry got up to leave, but he did not go right away. He leaned over the table and kissed the hand of Barbara Clark, the party vice chairman who had supported Sterling Tucker in the primary. The Barry strolled around the room, shaking hands, pecking cheeks and playing politics all the way.