John D. Negroponte, a veteran Foreign Service officer who as U.S. ambassador to Honduras played a key role in the military buildup of the Nicaraguan contras, will be named President Reagan's deputy national security adviser, administration sources said yesterday.

The sources said that Negroponte is scheduled to become the No. 2 to Lt. Gen. Colin L. Powell next week when Powell succeeds Frank C. Carlucci as the president's national security adviser. Carlucci will take over as defense secretary, replacing Caspar W. Weinberger.

Negroponte, a fluent speaker of Vietnamese, was the Vietnam specialist on the NSC staff of Henry A. Kissinger at the time of the Paris peace talks in the early 1970s. He reportedly considered the terms of the emerging agreement so damaging to South Vietnam that he quietly resigned his NSC post and was reassigned to a less important job in Ecuador.

Negroponte became ambassador to Honduras im 1982 as the U.S. policy of providing covert military aid to the Nicaraguan contras was getting under way. During his tenure as U.S. ambassador, the contras grew from a small band of disorganized guerrillas to a fighting force of 12,000 that was armed and equipped by the Central Intelligence Agency.

The United States also established a regional counterinsurgency training center where U.S. advisers instructed Honduran and Salvadoran troops.

Negroponte, now 48, was widely viewed by both supporters and critics of the contra policy as tough-minded and efficient. His influence over Honduran affairs was considered so significant that he was sometimes called the "proconsul." He enjoyed a close relationship with Gen. Gustavo Alvarez Martinez, then chief of the Honduran armed forces and an outspoken supporter of the contra cause.

After three years of controversial service in the Honduran post, he accepted an appointment as assistant secretary of state for oceans and international environmental and scientific affairs.

In that post, which he currently holds, he was responsible for coordinating the State Department response to the 1986 Chernobyl nuclear disaster in the Soviet Union and was a moving force behind the international protocol for protection of the stratospheric ozone layer signed in September.