Israel, hoping to capitalize on African fears of Libya's Col. Muammar Qaddafi, welcomed today the first black African head of state to visit here since 1971.

President Samuel K. Doe of Liberia, which earlier this month restored diplomatic ties with Israel, was greeted at Ben Gurion airport with full honors and an Israeli delegation headed by Prime Minister Menachem Begin and President Chaim Herzog.

The scheduled four-day Doe visit and Liberia's decision to become the second black African nation to restore ties broken after the 1973 Middle East war have fueled hopes here for a thaw in the 10-year freeze in Israeli-African relations.

In this, Israeli officials said they are receiving some unintended help from Qaddafi, a sworn enemy of the Jewish state, whose involvement in Chad and elsewhere in Africa is causing increasing alarm among African leaders.

"It doesn't hamper our chances," said one official who disclosed that in resuming ties with Israel, the Liberians had sought Israeli intelligence information on Qaddafi's activities in Africa.

In his welcoming speech, Herzog referred directly to what he called Libya's "new-style imperialism."

"You come from Africa, facing the new danger of Libyan colonialist ambitions, which threaten the independence of many African countries," the Israeli president said. "Your struggle against this new-style imperialism is a struggle with which we can identify and sympathize."

Herzog's theme is one the Israelis have been using, both in Africa and Central America, in a quiet but apparently aggressive campaign to identify themselves with other nations facing externally supported threats. Another recent manifestation of this Israeli diplomacy is the closer ties established between Israel and the embattled government of El Salvador.

Three weeks ago, a Liberian delegation composed of the minister for presidential affairs, the defense minister and the Army chief of staff visited Israel as a prelude to the announcement of a resumption of diplomatic relations. Despite the strong military presence in the delegation, Israeli officials said, the Liberians are not seeking arms or other military assistance from Israel because they already receive as much as they need from the United States.

But the military men in the delegation were interested in receiving "immediate information" on Qaddafi's Libya, according to an Israeli official knowledgeable about developments in Africa.

The official said the Liberians are concerned not only about Qaddafi's support for the rebels in Chad, but also about Libya's involvement in Upper Volta, the Central African Republic, Niger and elsewhere.

Libya was the first country to recognize Liberia following the bloody 1980 coup led by Doe. Shortly after the revolution, Liberian officials, expressing their concern over the need for resources, confirmed that Libya had made generous offers of aid. The offers were ultimately rejected, however, according to Liberian officials, when firm diplomatic and economic ties were established with the United States.

In addition to intelligence information, the Israeli official said the Liberians are interested in help for their country's agricultural development, establishment of a national shipping line and reorganization of the small Liberian national airline.

Doe is also said to believe that by being among the first black African leaders to resume formal ties with Israel, he will attract favorable publicity for the country and strengthen Liberia's ties to the United States.

These are clearly matters of interest to Doe, a one-time master sergeant in the Liberian Army who came to power in the country established in the 19th century by freed American slaves and where the U.S. dollar remains the national currency.

For the Israelis, the visit is a small but potentially significant step on the road back to acceptance by black Africa. Following the 1973 war, 26 African states cut their ties with Israel. To date only Liberia and Zaire--the last to break relations and the first to restore them last year--have resumed ties.

According to the Israelis, other black African states have expressed interest in resuming diplomatic relations with Israel but are faced with intense Arab pressure including--the Israelis charge--threats against the lives of African leaders.

But the Israeli official said Arab influence in black Africa is waning because major Arab countries such as Saudi Arabia have failed to make good on promises of assistance and preferential treatment.

The official indicated that he believes other African states are nearing a decision to follow the example of Zaire and Liberia, but he declined to speculate on the possibility.

Before Doe's arrival today, the last such visit here from black Africa was by a delegation of four heads of state in 1971. According to officials, Israel has commercial and other ties with 22 black African nations, but full diplomatic relations only with Liberia, Zaire and three smaller, relatively new states.