Housing and Urban Development Secretary Samuel R. Pierce Jr. is no longer expected to stay on if President Reagan wins reelection, and one possible successor, Undersecretary Philip Abrams, may beat him out the door.

Pierce, a former corporate lawyer, has weathered four years of strained relations with urban leaders, housing advocates and civil rights groups, and occasional disparaging comments from White House aides. He has remained a loyal soldier, campaigning widely as the chief black spokesman for the Reagan-Bush ticket.

But sources say Pierce has been in touch with his old New York law firm, and he recently told a reporter he has "given four years" and is thinking about moving on. He might remain for a transitional period in early 1985.

The insider most likely to replace Pierce had been Abrams, who runs the department on a day-to-day basis. But Abrams has made plans to return to the development business and may be gone before Inauguration Day. Assuming that Reagan is reelected, this makes it probable that the White House will look outside the department for the next secretary. INSIDE PUBLIC HOUSING . . .

Public housing tenants, who have borne the brunt of the Reagan administration's sharpest budget cuts, are disproportionately black, female and unemployed, a new survey says.

The survey by the Council of Large Public Housing Authorities drew responses from 64 agencies that manage 477,355 units, or 40 percent of the nation's public housing stock. In a revealing snapshot of the tenant population, it found that: More than three-quarters of the family units are occupied by minorities. A quarter of the authorities reported that their tenants are almost exclusively black. This breakdown is unlikely to change: half the authorities said that at least 75 percent of the families on their waiting lists are black.

* More than half the families are headed by women.

* Nearly two-thirds of the families are headed by an unemployed person. The median income of families in which the household head works is $7,908.

* More than a third of the families receive welfare benefits, a figure that rises to more than half at many big-city authorities.

* Demand continues to grow, especially for the 347,152 family apartments managed by the authorities. The agencies said 247,563 families are waiting for these units to become available.

The study noted that a greater proportion of the 172,000 tenants in New York City's sprawling housing projects are white, working families and fewer are on welfare. This more diverse mix may help explain why New York's housing agency has a reputation as one of the best-managed in the country.

Since Reagan took office, HUD has raised rents for public housing tenants, virtually ended construction and tried to cut operating subsidies. The agency recently has moved to sell some projects to low-income tenants, delayed a plan that could cut off subsidies for up to 40,000 vacant units and been sued by 13 authorities for trying to recoup alleged overpayments. KEEPING THE LID ON . . .

A recent memo from Federal Housing Commissioner Maurice L. Barksdale warned top officials "that no information . . . is to be released from the Office of Housing without a valid Freedom of Information Act request." A HUD spokesman attributed the memo to an overzealous staff member.