California Gov. Edmund G. (Jerry) Brown Jr. said yesterday he would establish diplomatic relations with Cuba if he should succeed in his bid to win the U.S. presidency.

Current U.S. policy toward Cuba "is an anachronism," Brown said on the television interview program "Issues and Answers" (ABC, WJLA).

"As long as this nation has relations with Russia and China, it makes no sense not to have them with Cuba," he said.

"There is no intellectual logic or consistency to a policy that sends an ambassador to Peking and Moscow" but avoids diplomatic relations with Cuba, he said.

Brown, an undeclared candidate for the Democratic presidential nomination, harshly criticized the Carter administration for its handling of the dispute with the Soviet Union over the presence of Russian troops in Cuba.

President Carter could cut off the sale of U.S. grain to the Soviet Union if he really wants to pressure the Soviets into withdrawing their troops, Brown said.

"The U.S. is feeding Russia on the one hand and then pouting and making noises at Cuba on the other," he said.

Commenting on his presidential chances, Brown said he is not disturbed by polls showing that he trails Carter and Sen. Edward M. Kennedy (D-Mass).

"I think I have a substantial posibility of winning the Democratic nomination. I will go as far as my resources will carry me," he said.