PRESIDENT REAGAN is about to make his first appointment to the Federal Reserve Board. He apparently intends to use the occasion to send a message of hope and good cheer to the savings and loan industry. Officials at the White House suggest that Mr. Reagan has chosen Preston Martin, a businessman with long experience in real estate finance. He was California's savings and loan commissioner when Mr. Reagan was governor, and subsequently became chairman of the federal Home Loan Bank Board, which has roughly the same regulatory relation to the S&Ls that the Federal Reserve has to commercial banks.

The White House is well aware of the deepening troubles of the savings and loan industry, caught between the low interest earned on past years' mortgages and the high interest being paid out on current deposits. The appointment of Mr. Martin is an indication, along with many others, that the administration's solution is ultimately to fold the S&Ls into the commercial banking system. The administration evidently wants someone at the Federal Reserve capable of overseeing this process.

That's reasonable, as far as it goes. But the banks are confronted with large and urgent troubles of their own. They arise not only from high interest rates, but from new and unexpected kinds of competition from institutions--money funds, investment houses, foreign banks--that are regulated under other rules, or not at all. The banks object that the administration is giving priority to averting one immediate danger--a wave of S&L failures-- while neglecting the deeper but less dramatic strains in the larger banking system. There is a growing drought of credit to many traditional customers, especially small businesses and farmers.

That's a serious point, and deserves more attention than the administration is giving it. But if Mr. Martin is perhaps not the bankers' ideal candidate, neither is he an ideologue or salesman for any narrow economic theory. Mr. Reagan had been getting a lot of highly partisan advice to appoint a Reagan loyalist who would press from within the Federal Reserve Board for the ideas of the political right. Mr. Reagan has recognized that suggestion as a particularly foolish formula for a disruptive quarrel within the nation's central bank, at a time when he seems to have very little fault to find with its actual course of action.