Sen. Carl Levin (D-Mich.) yesterday urged that CIA Director William J. Casey place his financial holdings in a blind trust, saying that Casey's heavy trading in the stock market last year "creates the appearance of using public office for private gain."

Levin was responding to the release of Casey's 1982 financial disclosure statement, which showed that Casey bought and sold millions of dollars in stocks and other securities last summer as the stock market was beginning a major advance.

Casey bought $3.8 million to more than $7.8 million in stocks, bonds and other securities last year, selling off other holdings to invest heavily in electronics and drug stocks, some of which have increased significantly in value.

Casey's longtime financial adviser, Richard Cheswick, said yesterday that he "had discretion to manage Casey's investments without consultation by him."

In a statement issued at Casey's request, Cheswick, a member of a Connecticut investment firm, said, "There have been no instances whatever during Mr. Casey's service as director of the Central Intelligence Agency that he has provided me with any information or special analyses which could be used as an aid in making these decisions." Cheswick said that similar advice was "consistently applied to our other clients' portfolios . . . . The stocks and bonds selected by us were deemed appropriate for his family's investment objectives."

Levin told President Reagan in a letter that unless Casey agrees to place his holdings in a blind trust, as several senior government officials have done, he will introduce legislation to require Casey to do so. A blind trust is an account that is managed by an adviser without the investor's knowledge.

A CIA spokesman has said that two other CIA officials review Casey's investments and recommend whether he should excuse himself from any matters because of possible conflicts of interests, but that such advice would not be made public.

Levin questioned how the two officials would "know just what issues might affect a particular company," adding, "It seems clear that the repeated stock transactions by Mr. Casey while he receives information on an ongoing basis as director of the CIA creates the appearance of using public office for private gain.