Sen. William L. Scott (R-Va), in what he said was his last press conference as a senator, announced yesterday that he will not resign before his term expires to give his apparent successor, Republican John W. Warner, seniority over other new Senators.

"I don't believe in resigning until the term is over, which is noon on Jan. 3," said Scott, adding, "it's wrong. We have priorities."

Because Warner does not have any of those priorities - former service as a member of Congress or governor - he and other new members who have no prior experience will be ranked alphabetically. According to William F. Hildenbrand, secretary to the Senate minority, means Warner will be last among the 41 Republicans in picking committee assignments and last among all 100 Senators in selecting office space, parking permits and other perquisites.

Scott, who did not seek reelection, appeared to be cool toward Warner, the apparent winner over Democrat Andrew P. Miller Jr. in the close and disputed Nov. 7 election.

At his press conference Scott recalled that he had enthusiastically supported Richard D. Obenshain for the nomination at the party's convention here in June. Warner was picked by party officials as the nominee after Obenshain was killed in a plane crash Aug. 2.

When a reporter mentioned that Scott had described Warner at the convention as "an actor," Scott said "yes, he was pulling an act, acting like a cheerleader" in appealing to delegates for votes between ballots. It was not a proper way to act at a convention," Scott said.

Has he changed his view of Warner? Scott was asked. "Mr. Warner is the nominee," he replied. "Jack (sic) Warner was the better of the two candidates."

Scott defended his decision to pass up the last five days of the 95th Congress, saying he was "not feeling well." He said he was suffering from "a nervous condition, my stomach was bothering me." To relax, he said he and his wife Inez took a three-week auto trip as far west as Arizona.

"No, no no it was not at government expense," he said. Scott tax-payer-paid trips to 38 foreign countries in the last couple years have brought him much criticism and ridicule.

Scott said that Congressional leaders "should not schedule matters of importance" in the closing days of any session because "very few people know what's going on.

"During the closing hours, all kings of things are stuck in," he said. Scott recalled that during one of his three terms in the House, he later discovered that in the closing hours of one session "had (mistakenly) voted for repeal of the Gulf of Tonkin Resolution. People are not aware of what they're doing. It's true of all the Senators."

During a discussion of his dozen years on Capitol Hill, Scott said his most significant accomplishment was "representing the people of Virginia in a conservative manner . . . reflecting the views of the vast majority of my constituents."

Pressed to identify a particular legislative achievement of which he was "establishing American Business Day," which he said passed the Senate "but the House would not consider it."

Scott said he could not recall the date of the proposed holiday, except that "it was the day the colonies (sic) landed at Jamestown in 1607."

Senate records show that Senate Joint Resolution 15, 1975, would have authority the President to proclaim May 13 as the day to salute business, much as the first Monday in September is called Labor Day.

When he retires early next year, Scott said he will receive "a very good (federal) pension" of $41,000 or $42,000 a year. Scott has been a U.S. employee 38 years, beginning in 1934, at age 19, as a pressman's helper at the Government Printing Office. Later he moved to Justice, where he was a trial attorney for 18 years.

"There is no question of double dipling," he said.

Scott, 63, said he plans to practice law with his two sons, as the fifth partner in their law firm in suburban Springfield.

"But it won't be a question of daddy teaching the boys," Scott said."They know how." He said he may not work full-time, but will "help them secure clients."

As the news conference broke up, Mrs. Scott, who had been listening in an adjoining office, berated a Washington Post reporter for failing "to investigate" whether Rep. Joseph L. Fisher (DVa.) had reimbursed the government for the cost of his wife's expenses on a congressional trip to Portugal.

Fisher's office said yesterday, and the Senate clerk's office confirmed, that he paid the government $431.25 on June 22 as his wife's share of expenses on the trip.