President Reagan yesterday named James M. Stephens, a former aide to Sen. Orrin G. Hatch (R-Utah), to be chairman of the National Labor Relations Board.

Stephens, a member of the board since 1985, replaces the controversial Donald L. Dotson who was not reappointed when his term expired last month.

Stephens does not have to be confirmed by the Senate, and will serve at the pleasure of the president.

Reagan also is expected to nominate John E. Higgins Jr., a career NLRB employee who is deputy general counsel, to the board.

The Stephens appointment was generally praised yesterday by Republicans and Democrats. The one notable exception was the National Right to Work Committee which described the appointment as an act of "open hostility" by the Reagan administration.

A former labor counsel for the Senate Committee on Labor and Human Resources, Stephens, 41, was a management lawyer before entering the government in the late 1970s.

In a statement released by the NLRB yesterday, Stephens said he would work closely with other members of the board in administering the National Labor Relations Act. "To the nation's employees covered by this law, I pledge to discharge my new responsibilities with hard work, a commitment to fairness and a belief in our system of peaceful industrial relations through law."

Stephens was praised by union officials and congressional Democrats yesterday as intelligent and open-minded. "He's a pretty reasonable guy, he believes in the act and the process," a congressional Democrat said.

Colleagues described Stephens as someone who works hard and is not an idealogue. "He actually reads the cases," one source said.

Rex Hardesty, chief spokesman for the AFL-CIO, said "certainly Stephens will be a better NLRB chairman than Dotson and therefore workers will be better off with Stephens."

Dotson, who frequently fought with fellow commissioners including Stephens, was despised by organized labor. A former general counsel of the Wheeling Pittsburgh Steel Corp., Dotson worked hard to reverse what he saw as the pro-labor tilt of the NLRB. By the time his term expired late last year, it was clear Dotson would face a bruising confirmation hearing if renominated.

The biggest concern of Democrats and Republicans yesterday was who would be appointed to fill the Dotson vacancy. Whoever is appointed will serve through the first term of the next administration.

The Higgins nomination is expected to win support of most mainstream groups.

The major opposition is expected to come from the National Right to Work Committee which has openly warned the White House last month it would consider both Stephens and Higgins appointments "outrageous . . . in the eyes of the 68 percent of Americans who oppose compulsory unionism."

Government sources said yesterday that the Higgins nomination is a certainty. "He's going to get it," one source said.

One source said the only reason he was not nominated yesterday was that FBI checks had not been completed.

A spokesman for the Right to Work Committee said the holdup was opposition from his group and other conservatives.

Sources said Salvatore Martoche, assistant secretary of labor for labor management standards, was the other leading candidate for the NLRB vacancy before the White House decision to go with Higgins.