The first chairman of the Senate Intelligence Committee, former senator Frank Church, said yesterday that the Reagan administration's proposed executive order on intelligence is "as unwise as it is unwarranted."

Testifying before a House Judiciary subcommittee, Church said the latest version of the proposal to surface publicly was "plainly designed to enlarge the role of the CIA inside the United States, with respect to spying on American citizens and conducting covert operations in our own country while diluting the role of the Justice Department as a check on the legality of these activities."

Church, an Idaho Democrat who headed the Senate investigation of CIA and FBI excesses and illegalities in the mid 1970s, said it was a misfortune that that inquiry did not lead to enactment of a legislative charter for the intelligence community.

The result, he said, has been to make the rules subject to change every four years, dependent "on the accusations made, and promises given, in the heat of the most recent presidential campaign."

"Our civil liberties are too precious to be toyed with in this manner," Church protested at a public hearing before the House civil rights subcommittee headed by Rep. Don Edwards (D-Calif.).

There have been reports that the White House is revising the proposal again in light of congressional criticisms and that it may remove at least one major bone of contention: language giving the CIA authority to infiltrate and under some circumstances influence the activities of purely domestic organizations in this country.

Church, however, said that change alone would not be sufficient in his view. Other provisions of the proposed order, he said, would still permit the CIA to conduct covert actions and to use intrusive methods in order to "collect information" from law-abiding Americans in this country, even if they are not suspected of acting on behalf of a foreign power.

"I would leave the line where it is now drawn in the existing order" issued by President Carter in 1978, Church said. He said the FBI was much better equipped to carry out whatever operations are needed in this country since its agents are attuned to law enforcement.

By contrast, Church said, "the CIA in its normal work, operates in utter disregard of the consequences of the law" of other countries. "Its people are trained to break the law abroad . . . or they would get precious little intelligence . . . . When you bring those people home, you invite trouble, serious trouble."

Chairman Edwards said he was also concerned with other aspects of the draft executive order that would drop restrictions on CIA funding of local and state police agencies and could allow the resumption of old and controversial relationships.