The new Marine Corps commandant went on record yesterday as favoring the registration of both men and women for the draft and warned that conscription will have to be considered by "the mid to late 1980s."

Gen. Robert H. Barrow, who succeeded Gen Louis H. Wilson as the 27th commandant of the 184,000 - Member Corps last Sunday, stressed in his first news conference since becoming the nation's top Marine that he was not yet ready to give up on the idea of an all-volunteer military.

"It would be a mistake" to go back to the draft right now, said Barrow, because the all - volunteer military force is "generally working."

But the declining population of 18 - year - olds and the growing disinclination of young people to join the military, Barrow said, will make it increasingly difficult to fill the ranks with volunteers in the 1980s.

To prepare for that contingency, he recommended "moving toward" draft registration now and considering conscription later.

The House Armed Services Committee has approved a defense procurement bill that contains a provision to require men, but not women, who become 18 on or after Jan. 1, 1981, to register. The House is expected to vote on the measure later this month.

To keep the ranks of all the services filled these days, Barrow said, military recruiters must sign up an average of 1,000 volunteers a day, 365 days a year. "We're doing it," he said, but with difficulty.

He said taking in more women than planned would not ease the coming personnel crunch for the Corps because women cannot, by law, fill such combat jobs as rifleman, artilleryman and tank driver.

"I personally think the law is right," Barrow said of the ban on women in combat. "I see no reason in the world women should have to be engaged in direct combat." He said they have proved to be "a big plus" for the corps in noncombat jobs, however.

Currently, 2.5 percent of the 18,289 officers and 3 percent of the 165,643 enlisted persons in the corps are women. Barrow said the Marines intend to double those percentages by the mid-1980s.

Barrow's warning abo* ut running out of volunteers was part of a generally "tough soldier" theme the new commandant sounded yesterday.

Asked what worried him most as he surveyed the nation's military problems, Barrow replied: "The national will to have the kind of security this country needs. We're lagging not only in strategic forces" but "in conventional" power as well.

National leaders get their direction from "the will of the people," he continued. "I wish the people would raise their voices and ask for a stronger defense."

Once the national will is expressed, he said, "use it." He said he had no particular area of the world in mind where he would like to see the national will exerted, adding that he probably would not say so even if he did.

Barrow, 57, is the only member of the Joint Chiefs of Staff who was in combat in World War II. He said today's Marine Corps is ready to fight anywhere in the world, including the middle of the NATO line as well as its flanks. The corps is making no special plans for meeting Persian Gulf contingencies, he said.

The new commandant sounded less enthusiastic than his predecessor about spending millions to buy the AV8B Harrier jump jet, which Pentagon leaders consider a luxury the Marines can do without.

"It's difficult for a service of our size to bear the burden" alone of buying such an advanced and expensive aircraft, he said. "If we could get some foreign governments interested, and some other services" interested in buying the AV8B, "we would have a better time of it." CAPTION: Picture, Gen. Robert barrow: "I wish the people would . . . ask for a stronger defense." By Frank Johnston - The Washington Post