While he has been teetering on the high wire of Middle East diplomacy this month before an anxious world, Jordan's King Hussein has been watching apprehensively his most important safety net--the billions of dollars that flow into his poor desert kingdom from Arab oil countries.

The importance of money to the diplomatic process that has engaged Hussein and PLO Chairman Yasser Arafat in an on-again, off-again dialogue over President Reagan's peace initiative for the past month has been scarcely commented upon in public, but the dark clouds that loom on the financial horizon for Hussein are clearly visible to the key players in the continuing drama.

When Saudi Arabia's foreign minister, Prince Saud Faisal, arrived in Amman shortly before Hussein and Arafat began their talks on April 2, he carried not only words of support for the negotiations from the Saudi royal family but also a package of several million dollars for Hussein's national treasury as a concrete sign of support, Arab sources have disclosed.

Hussein's announcement last Sunday that the talks had collapsed has underscored Jordan's financial vulnerability once again as the oil-producing countries, which also bankroll Arafat's Palestine Liberation Organization, assess the failure and apportion the blame.

There were no visible signs here today that continuing private and public statements from Arafat and his aides that they wanted to continue the talks are producing a reassessment by the Jordanians of Hussein's declaration Sunday. Hussein said that the talks had been made pointless by Arafat's abrupt departure from Amman and last-minute changes the Palestinians had demanded in a draft agreement the two Arab leaders had reached last week.

Arafat flew from Tunis to Algiers today to meet with President Chadli Bendjedid, news agencies reported. PLO officials have been gathering in Tunis for a high-level meeting to discuss resuming the talks with Jordan, but the date of that meeting remains uncertain, Palestinian sources said.

New details on usually secret financial dealings between the Arab oil countries and Jordan have emerged in the wake of the publication this week by The Wall Street Journal of private communications between Hussein and other world leaders in articles apparently authorized by the king. Saudi Arabia appears to have been particularly stung by a strong suggestion in the articles that Prince Bandar ibn Sultan made an implied threat to Hussein that the Saudis would end a vital subsidy for oil imports unless Hussein is forthcoming in the talks with Arafat.

As part of the subsidy granted by the 1978 Arab summit in Baghdad to compensate Jordan for its opposition to the Camp David peace treaty between Egypt and Israel, Saudi Arabia has been selling $34-a-barrel oil to Jordan for about $5, a responsible Arab source reported.

Contacted in Washington, Prince Bandar, who is King Fahd's nephew and has served as a mediator between Hussein and Arafat, denied that he had delivered any threat to Hussein. "Saudi Arabia continues to subsidize oil sales to Jordan, and Saudi Arabia continues to affirm its support for Hussein. Saudi Arabia also is adamant in not discussing communications between heads of states."

Jordan, barren of significant natural resources or industry, relies on imports for food and energy. Its trade deficit last year has been estimated at $2 billion.

The last decade has been one of an economic boom, however. Jordan has experienced a surging annual economic growth rate of 8 percent for most of that time although it dropped last year to about 5.5 percent. There is virtually no unemployment here and most of the unskilled labor is imported.

The annual $1 billion sent home by the 310,000 Jordanians working in the Persian Gulf and the aid from the oil states, which has topped $1 billion annually in recent years, are the pillars of Jordan's economy.

Although the United States has promised to allow Jordan to buy sophisticated U.S. weaponry if it agrees to come into negotiations with Israel, the indications are that Washington has not made any commitments for the kind of increases in economic aid that might be needed if Jordan is excommunicated from the Arab world, as Egypt was after Camp David.

In Jordan's case the results would be considerably worse. This is one of the chief reasons why Hussein stresses that he needs the support of moderate Arab states for whatever steps he takes.

Moreover, businessmen and others here are already uneasy about the health of the economy. There is uncertainty about how the drop in oil prices will affect Jordanian workers in the gulf and the aid from the oil states; the war between Iran and Iraq has already begun to take a toll on Jordan's economy.

About 80 percent of the financing for the vast public works activity here has come from outside; about half of Jordan's operating budget is externally financed. At the Baghdad summit, Saudi Arabia, Kuwait, Iraq, the United Arab Emirates, Qatar, Algeria and Libya pledged a total of $1.25 billion in annual grants to Jordan.

Libya never paid, and Algeria did so only in the first year. As a result, Arab aid to Jordan in 1979 and 1980 was about $1 billion. Two years later, however, the five remaining donors agreed to make up the Libyan and Algerian payments, which they did for 1980 and 1981.

In 1981 Hussein drew up a five-year capital development plan with the expectation that the aid would continue to be about $1.25 billion. But foreign economic anlysts say the indications are that the funding dropped off again last year and might fall to about $800 million or $900 million this year.

Kuwait reportedly told Jordan last fall it was not going to make up the Libyan and Algerian shortages, and Iraq, because of its economically draining war with Iran, is thought to be unable to continue to pay its share.

As a result, Hussein began to pare back last year on his capital development plan.

He also created a short-term loan program last year for Jordanian businessmen whose once-strong trade with Iraq has slowed to a trickle.

For those reasons, there was perverse relief among some here after the Hussein talks with Arafat failed--relief that, for the moment, at least, the Jordanian monarch had not taken steps that they feared could end Arab aid and send home Jordanian workers in the gulf.