The White House announced yesterday that President Reagan will nominate Heather Gradison, who is the wife of a Republican congressman, to be a member of the Interstate Commerce Commission. If confirmed by the Senate, she will replace Robert C. Gresham, a Republican whose term expired at the end of last year.

In a related development, the Senate finally has confirmed Republican Frederic N. Andre, a transportation consultant, to be a member of the transportation regulatory agency. His nomination had been pending at the Senate for more than five and a half months. Andre replaces Charles I. Clapp, a Republican whose term expired at the end of 1980 but who, under the ICC statute, has been able to continue to participate in agency business until actually replaced.

Another more recent Reagan nominee, J. J. Simmons III, vice president of government relations for Amerada Hess Corp. and a Democrat, reportedly will be confirmed shortly.

Gradison, 29, a Republican, worked at Southern Railway for six years, most recently as a rate officer; she took a leave of absence last fall. Her job at Southern was described as a professional position without decision-making authority. According to Southern, a rate officer is responsible for a certain group of commodities, doing research on the railroad's costs of moving the items as freight, and the competitive situation. He or she then works with shippers and receivers to negotiate a satisfactory freight rate, making recommendations to a rate manager, who makes the final determination.

If Gradison is confirmed for the position, her past employment with Southern could require her to disqualify herself on issues affecting the railroad. The ICC's canon of conduct states that members should disqualify themselves "in any matter in which their impartiality might reasonably be questioned."

Gradison is the wife of Rep. Willis D. Gradison Jr., a Republican representative from Cincinnati who is a member of the Ways and Means Committee.

If all the Reagan appointees take their places on the commission, it will have four Republicans and two Democrats--a lopsided split that some on the Democratic side have complained about. The full complement also will mean that President Reagan has appointed five of the six members, including the controversial chairman, Reese H. Taylor Jr. The only holdover from the Carter administration is Democrat Reginald E. Gilliam Jr., whose term expires at the end of this year.

Hill sources expect the new composition to result in ICC decisions that are more pro-deregulation than decisions have been in recent months, although not as deregulation-minded as the ICC appointed by the Carter administration. By law, the agency can have as many as 11 members.

Andre's confirmation this week came quickly after a month-plus hold on his nomination was lifted by Sen. John Melcher (D-Mont.). Senate sources said Melcher lifted his hold after being told by Sen. Howard W. Cannon (D-Nev.), ranking minority member of the Commerce Committee, that he and Committee Chairman Bob Packwood (R-Ore.) were prepared to ask the Senate's Republican and Democratic leaders to begin action on the delayed nomination despite Melcher's hold.

Melcher reportedly held the nomination on behalf of ICC member Clapp, whom Andre would replace. Sources also said that Roy Williams, general president of the Teamsters' Union, personally went to the White House to lobby for Clapp's reappointment. The White House's refusal to retain Clapp on the ICC has been seen by some as a slap at the Teamsters, one of the two unions to support Ronald Reagan's election to the presidency. The other union was the Professional Air Traffic Controllers Organization.