Carter administration officials are showing up in the lobbies, lounges and meeting rooms of the Pittsburgh Hilton in an all out effort to convince the nation's mayors to support de-control of oil prices.

The setting for the unabashed lobbying is the 47th annual U.S. Conference of Mayors, which opened here today.

Oil price regulation is one of the major issues being debated at the five-day conference, which will conclude with a series of resolutions on a wide variety of matters affecting urban life.

The resolution are important.They will be used to help guide the nation's mayors in their dealings with Congress next year.

"That's one of the major reasons we are here," said Ralph Schlosstein, a legislative assistant on the White House domestic policy staff.

"We're obviously searching for support wherever we can find it, and we're also trying to avoid criticism wherever we can . . . We need the mayors with us on the decontrol issue," Schlosstein said.

"Frankly, I believe the administration has contacted every damned mayor on the [47-member] conerence energy committee," said a ranking member of the mayors' organization who requested anonymity. "It almost makes you wonder if the White House doesn't have anything else better to do."

The primary object of the administration's attention are two conference resolutions, numbers 17 and 18.

Resolution 17 urges Congress to continue controls on oil prices on grounds that decontrol would cost consumers an estimated $17.6 billion in higher fuel prices while doing little to increase energy production. If Congress nevertheless supports President Carter on decontrol, Resolution 17 calls for institution of a "strong, permanent excess profits tax" on oil prices identical to the so-called "windfall profits tax" supported by the Carter administration.

Resolution 18, the one being pushed by Carter officials, strongly supports the phased decontrol of oil prices that began June 1. It also calls for the windfall profits on decontolled prices.

"We couldn't support Resolution 17 because, though Congress could reimpose controls, phased decontrol has already started," said Thomas Tatum, urban liaison for the Department of Energy.

Both resolutions urge that any windfall profits tax be funneled into a proposed energy security trust fund to be used for improving local mass transportation, helping low-income persons meet rising energy costs, and encouraging accelerated energy research and production. It is a selling point that administration officials stress repeatedly in discussions with the more than 300 mayors and city officials here.

Tatum said the administration estimates that the energy security fund would receive $2.5 billion by 1981, when oil price controls would end completely. State and local governments would receive up to same year, and the federal government would reap an estimated $5.4 billion extra tax revenue, he said.

For their part in 1981, oil companies would keep $3.4 billion of new revenues spawned by decontrol, Tatum said. "We think it's the best way," he said.

The administration will have three chances to convince the mayors that its position is correct.

Preliminary hearings and votes are being held today and Sunday on the oil price regulation issue. The full conference will have the final say on Wednesday when the meeting ends.

"If the mayors support decontrol in the preliminary seesions, that's important," Schlosstein said laughingly. "If they don't support us in those first seesions then it's not important, because we're going to keep working until the final vote comes."