A high-level U.S. delegation flew to Paris this week with plans to help modernize one of the world's more complex and slow-moving bureaucracies.

The target is The Coordinating Committee for Multilateral Export Controls, or Cocom. Its task is to screen sales of technology going from western nations and Japan to communist countries.

During the past year, the organization has been flooded with applications from American businessmen hoping to sell technology to China.

Most of Cocom's own technology is primitive. With only a handful of word processors, it has barely made the transition from the mimeograph to the computer age.

American officials attending the Cocom meetings in Paris today include Lionel H. Olmer, undersecretary of commerce for international trade, and Richard N. Perle, assistant secretary of defense for international security affairs. They are to be joined on Thursday by William Schneider Jr., undersecretary of state for security assistance, science and technology, who leads the American delegation.

Given the sensitivity of its task and the multinational membership, Cocom is a secretive organization. The two days of talks in Paris are not expected to result in any public announcements. Cocom members are the NATO partners, excluding Iceland, and Japan.

U.S. officials said the modernization and the increase in sales to China are to be two major items on the agenda. According to these officials and to American businessmen who are concerned with delays in Cocom approvals for sales to China, it would take up to $2 million to make Cocom more efficient.

When it comes to sales to Peking, Cocom is not the only problem. Some officials point to delays within the U.S. Commerce Department. Officials there argue, however, that they have improved their part of the system, with more than 4,400 export licenses for China approved in 1984, compared to about 2,800 in 1983. A department official said that the value of the sales resulting from these approvals had risen from about $930 million in 1983 to about $2 billion in 1984.

The official said that a major increase in applications for export approvals for China had nearly overwhelmed Cocom and "required almost all the assets they've got to deal with China cases."

"It's detracting from the need for serious examination of the cases concerning exports to the principal adversary of the West, the Warsaw Pact," the official said.

The sharp increase in applications for exports to China followed the Reagan administration's 1983 decision to liberalize the rules regarding exports to that nation of such items as computers.

Cocom was established after World War II as a small, informal organization. Officials say that it was accorded little sustained attention from Washington until the Reagan administration came to power.

The secretariat in Paris operates out of an American Embassy annex. Last year, the U.S. Defense Department gave Cocom a photocopying machine to replace the small, table-top machine which it had been using, an official said.

The United States is expected to propose a modest increase in office space and in translators and clerical workers on the small staff.