President-elect Ronald Reagan said today that the secret bombing of Cambodia "made a lot of sense," and that there is little purpose served by questioning his choice to be secretary of state, Alexander M. Haig Jr., about the bombing and Watergate matters.

"I think there's a certain amount of politics going on in this hearing," Reagan said of the Haig confirmation hearings. "I think they're trying to make a fuss out of something, but I've been watching some of the television . . . and I think he's taking care of himself pretty well."

When Reagan was asked whether it was appropriate for Haig, who was President Nixon's deputy national security affairs adviser and later chief of staff, to be asked such questions, he replied, "There are certain elements of extremism that get into the questioning that don't really have any bearing on whether he's going to be a good secretary of state. He is going to be a good secretary of state."

He made clear his strong feelings about the Cambodia bombing, which began in 1969 without the knowledge of Congress or the people.

"If you come down to Cambodia in the Vietnam war, the North Vietnamese were taking refuge, sanctuary in Cambodia, and coming across a line and killing Americans. And I think that going over after them so they didn't have a sanctuary made a lot of sense," Reagan said. He added: "And so did the fellas that were being bombed," in what he presumably meant to be a reference to the American and South Vietnamese forces that were fighting the North Vietnamese in Vietnam.

Reagan spoke to reporters, after getting a haircut from his Beverly Hills barber, as he paid his last visit to California before his inauguration.

Reagan said he thinks all of his Cabinet nominees will be confirmed, but made clear that he doesn't think too highly of the confirmation process.

He also answered questions about his economic plans, and said it has not yet been decided whether his promised tax cut should be retroactive to Jan. 1, as he said during the campaign, or should take effect from the time his economic program is passed.