After ducking almost out of view as more conservative policies swept through the the capital, consumerist Ralph Nader surfaced this week with a massive study of the Reagan administration.
Titled ''Reagan's Ruling Class: Portraits of the President's Top One Hundred Officials,'' the 730-page volume focuses on one major theme. Says Mr. Nader, ''Reagan has turned over control of the US government to a group of officials with a remarkably similar and limited set of experiences and allegiances that are remote to the realities of life for most Americans.''
Published by Nader's Presidential Accountability Group, the study details backgrounds and records, as well as including some 50 interviews with Reagan appointees.
Nina Easton, who cowrote the book with Ronald Brownstein, concludes that the study of the 100 office-holders pointed to their ''sameness.'' Almost 30 were found to be millionaires, and 95 were men, while all except two were white, she says.
Charging that the government under President Reagan is dominated by corporate interests, Nader calls it ''government of General Motors, by Du Pont, for Exxon.'' And he says that ''it was almost impossible after hundreds of hours of interviews to elicite any words of compassion'' from the administrative officials since they apparently wanted to avoid being labeled ''bleeding heart liberals.''
Not only did he find no liberals among the ''top 100,'' but Nader echoes a criticism now being leveled by many conservatives. Reagan officials also have ''disdain'' for the so-called New Right and libertarians, says Nader.
Those conservative groups who helped elect Mr. Reagan have been ''thoroughly replaced by representatives of business who seem to have as little time for debates on school prayer and abortion as they do for promoting the government's health and safety functions,'' according to the consumer activist.
Among the top Reagan officials, Nader singles out Treasury Secretary Donald T. Regan as the brightest and most influential. And he gives the highest marks to Gerald Carmen, who heads the General Services Administration, the government's giant procuring agency, which had been shaken by scandal in the Carter administration.
However, for the most part, Nader gives low scores to Reagan appointees. He calls Energy Secretary James B. Edwards the ''least competent'' because of his lack of knowledge about energy and criticizes Agriculture Secretary John R. Block for efforts to cut back government inspection of meat and poultry.
Nader says that his group made the study in an effort to put faces on the giant government bureaucracy, in the belief that the public will take more of an interest. ''The bureau-cracy will become more accountable if the known bureaucrats become more accountable,'' he says.