The League of Arab States celebrated its 36th anniversary last night with a banquet at the Washington Hilton Hotel attended by 500, including representatives of Arab nations from Algeria to Yemen. A stunning feature of the evening was a series of color slides of Arab architecture, landscape and people flashed on an enormous screen during the cocktail hour, all of them shot by architect Mokhless Al-Hariri.

The League's ambassador to the United Nations and the United States, Clovis Maksoud, and his wife received guests, among whom were Dr. Ali Elhoudeiri, representing the Libyan government here; Roger Chaufournier of the World Bank; the ambassador of Sudan, Omer Salih Mohamed Eissa; the ambassador of Tunisia, Ali Hedda; Mrs. Nouha Alhegelan, wife of the ambassador of Saudi Arabia; the ambassador of Yugoslavia, Budimir Loncar; the ambassador of the United Arab Emirates, Saeed Al-Shamsi.

Among the Americans present were former U.N. Ambassador Donald McHenry; George Sherman Jr., representing the State Department; former Senator James Abourezk, who was heard speculating that the evening must have cost in the neighborhood of $25,000; Rep. Philip Crane (R-Ill.); former senator Mike Gravel.

The food, which was on the magnificent side, started with Arab hors d'oeuvres of half a dozen sorts and thin chewy bread, followed by kebabs of both lamb and chicken, followed by numerous Arab sweets, all accompanied by various French wines.

A continuing and chief concern of the league is that justice for the Palestinians should be realized. A typical comment was perhaps that of Helen Haje, an American of Lebanese descent and a resident of Washington for 40 years. She was left a widow early in marriage and raised three children despite many difficulties:

"In Lebanon 20 to 40 people are killed every day, but what difference does that make to the world? It is a hemorrhage that must be stopped. But I have no hope whatever from our present administration -- I had hoped, but now I see no hope."

Maksoud also spoke of a resolution of the Palestinian problem in his remarks, as guests downed their lemon sherbet and baklava-like desserts called cigars (for their shape), and washed it all down with champagne. He noted that the Reagan administration had taken a pragmatic approach, and said the Arab League should do likewise, but did not get more specific than that.

With politics out of the way, league information director Michel Nabti introduced Professor Mohmmed Al-Akkad, who made glorious music on a kind of zither, known as a quanun.