In an effort to reduce government participation in Canadian business, the Canadian government yesterday announced its intention to sell four state-owned companies.

They are Canadair Ltd. and de Havilland Aircraft of Canada Ltd., two aircraft manufacturers; Eldorado Nuclear Ltd.; and Northern Transportation Co., a firm with trucking, shipping and barge operations.

"Selling some Crown corporations will help us achieve a leaner and less expensive government," Sinclair Stevens, president of Canada's Treasury Board, said in announcing the move.

Of the four companies slated for sale, all but Northern Transportation are profitable. Canadair, which produces the Challenger, the world's first widebodied business jet, had a net profit of $3.2 million on sales of $83 million last year.

De Havilland has been producing the Twin Otter and more recently the quiet, short-takeoff-and-landing Dash-7 which begins service from Washington for Ransome Airlines next week. It had a net profit of $1.9 million on sales of $170 million in the year ended May 31.

Eldorado Nuclear had a net profit of $17.6 million sales of $124.1 million in calendar 1978.

Stevens said that Northern Transportation, which had a net loss last year of $341,000 on revenue of $26.4 million, wouldn't be sold unless the potential new owner would be prepared to continue the public policy objectives now served by the company.