The state judicial board of inquiry that will investigate the massacre of Palestinian refugees in Israeli-occupied West Beirut was appointed today by Israeli Supreme Court Chief Justice Yitzhak Kahan, who named himself as chairman.

Kahan, who presented the list of board members to Prime Minister Menachem Begin, appointed fellow Supreme Court justice Aharon Barak and Army reserve Maj. Gen. Yona Efrat to serve with him on the three-member board.

The Begin government, which has denied any Israeli responsibility for the Sept. 16-18 massacre, authorized creation of the investigative board Thursday under intense domestic and international pressure. The panel is expected to begin its work after the week-long Jewish festival Sukkot, or the Feast of Tabernacles, which began tonight.

The board's makeup was viewed here as solid if somewhat colorless. Kahan, 69, the chairman, has been a judge since shortly after Israel achieved statehood in 1948. He has headed the Supreme Court for about a year and faces mandatory retirement at the age of 70.

Barak, 46, is one of the youngest judges on the Supreme Court. Before being named to the court, he was appointed Israel's attorney general, an independent, nonpolitical post, by the opposition Labor Party when it was in power. Barak remained in that job after the Begin government came to power in 1977 and accompanied Begin at the Camp David peace conference in 1978.

Efrat, 56, was born in Poland and has served as assistant to the Army's chief of operations and as commander of the Army's central command. Although he has led elite combat units, he is better known for his administrative abilities.

It is not clear how long the inquiry board, which is a fact-finding panel with power of subpoena but no authority to file legal charges, will take to complete the investigation. Kahan reportedly believes the task should be accomplished as quickly as possible, and estimates have ranged from six weeks to several months.

There is a widespread expectation that the investigation, during which public comments on the massacre will be restricted, could provide a lull in the intense political developments that have swept over Israel in the last several weeks.

The Jerusalem Post, quoting reliable sources in Begin's Herut Party, said today that Begin plans to push for elections next spring after the inquiry board reports its findings.

Before the massacre, Begin had threatened to call elections in the spring to test popular support for his rejection of President Reagan's Middle East peace initiative. That threat initially was greeted with much skepticism because several of Begin's coalition partners oppose early elections.

The newspaper also published the results of a public opinion poll that indicated, as did another published earlier this week, that the Beirut massacre has eroded Begin's popular support but not placed him in immediate serious political danger.

While Begin's ruling Likud coalition had stood to win an absolute majority of 66 seats in the Israeli parliament during the height of support for the war in Lebanon in August, it still would win 60 seats, 11 more than the Labor Party, according to the poll.