Ephraim Evron, Israel's ambassador to the United States, will resign his post at the end of January, the Israeli Foreign Ministry announced today.

The Foreign Ministry did not say who would be nominated as the new Washington envoy, but informed sources said Evron's successor is certain to be Moshe Arens, chairman of the key Foreign Affairs and Defense Committee of Israel's parliament, the Knesset.

A Foreign Ministry spokesman said that Evron, who has been ambassador to the United States since June 1978, advised Prime Minister Menachem Begin in July that he wanted to resign. Evron has been in public service for 33 years, mostly with the Foreign Ministry, and before being posted to Washington he was director general of the ministry.

Both of Evron's predecessors, Yitzhak Rabin and Simcha Dinitz, served in the post for five years, the normal term for an ambassador. Begin and Foreign Minister Yitzhak Shamir had been known to be displeased with Evron, particularly with respect to U.S.-Israeli relations after the election of President Reagan. But Shamir today said he and Begin "express our profound appreciation for the ability and attachment to duty shown by Ambassador Evron in representing the state."

Arens, an ultraconservative member of parliament who voted against the Camp David peace treaty in March 1979, long has been a supporter of Begin's Herut party, the nucleus of the ruling Likud bloc.

Born in Lithuania, Arens immigrated to the United States as a child and grew up in Philadelphia, where he became active in Betar, the youth movement of the Zionist revisionists led by Zeev Jabotinsky and, later, Begin.

In 1948, he immigrated to Israel and was active in Israel's war of independence, after which he studied at the Technion. He returned to the United States for graduate engineering studies at Massachusetts Institute of Technology, and later taught aeronautical engineering at the Technion, in Haifa. He also served as an adviser to Israel Aircraft Industries Ltd. and was involved in the development of Israel's Kfir jet fighter, modeled after France's Mirage.

Although he voted against the Israeli-Egyptian peace treaty, largely over the issue of dismantling Jewish settlements in the Sinai Peninsula, Arens later supported the Camp David peace process and the negotiations for autonomy for the Palestinians of the West Bank and Gaza Strip.

Although frequently mentioned for Begin's Cabinet, he never took a ministerial post, reportedly attributing his reluctance to his original position on Camp David. After the assassination of Egyptian president Anwar Sadat, Arens rejected appeals by some of his colleagues in the conservative wing of Likud to support their attempt to cancel the peace treaty and retain the remaining occupied portion of the Sinai.