RONALD Reagan's "favorite newspaper," the conservative weekly Human Events, is giving him fits lately.

Its headlines are reading like something from the editorial pages of one of those "liberal eastern establishment" newspapers it is forever railing about: "Haig Must Go" . . . "White House Staff Blows IRS Case" . . . "White House Continues to Fumble School Tax Issue" . . . "Is Reagan Foreign Policy Different from Carter's?"

What's up anyway?

There aren't two more committed true-blue-Reaganite-to-the-core conservatives anywhere than Thomas S. Winter and Allan H. Ryskind, the odd-couple owners of Human Events. They've been touting Reagan in the pages of their tabloid since the days when he did commercials for "20 Mule Team" Borax on TV.

Reagan has noticed the change. "I'm still reading you guys, but I'm enjoying it less," the president told Winter and Ryskind during a recent meeting.

They appear an unlikely pair. Winter is tall, tanned and well dressed with a shaggy gray mop of hair. A graduate of Harvard business school, he carries the title of editor, but is more the businessman and political activist of the two. He, for example, was one of the movers and shakers behind a recent Conservative Political Action Conference that attracted Reagan and most of his Cabinet.

Ryskind, the Capitol Hill editor, is short, intense and balding. The son of a Hollywood screenwriter, he regularly writes most of the first three or four pages of the paper, founded as a four-page newsletter in 1944. He is a masterful reporter and a committed ideologue with scores of contacts among Washington conservatives.

Reagan has a longstanding special relationship with Human Events, which has a national circulation of 50,000. He reportedly has been a faithful reader since the early 1960s.

It is also must reading at the White House. Each Friday, 24 copies of the freshly printed paper are delivered to 1600 Pennsylvania Ave.

"The president reads it, and you bet everyone else around here reads it, too," says White House intergovernmental liaison Richard S. Williamson. "You want to know what the president knows."

Human Events first spotted the former movie actor as a potential conservative spokesman in 1964, and unabashedly promoted his career.

The president has returned the favor. As early as 1966, Reagan, then running for governor of California, signed a subscription solicitation letter for the newspaper. He said he found "Human Events of great help these last several years," and looked "forward to each issue."

Reagan also has used information from the newspaper in speeches. A photo on Winter's desk shows candidate Reagan writing a speech on a legal pad as he consults Human Events. During the 1980 campaign, aides tried to wean Reagan from the paper by hiding copies of it from their boss.

Others have used the pages of Human Events to send messages to Reagan. In 1980, David Keene, the political director of George Bush's presidential campaign, wanted to suggest that Reagan pick Bush as his running mate.

Keene had been a Reagan insider in 1976, but he knew Reagan aides considered him a deserter because he had gone to work for Bush. Knowing he couldn't meet with the candidate, Keene presented his case in a Human Events article.

"I did that precisely because I knew it would get through to Reagan," he says. "I told them that's why I wanted to write it."

Winter and Ryskind insist they remain Reagan loyalists. "There are very few people in public life whom I instinctively agree with more than Ronald Reagan," says Ryskind. "We're on a very similar wavelength. I think that's why we like him and why he reads us."

Both say the newspaper's criticism of the Reagan administration is meant only as friendly advice, the kind a concerned father might give a wayward son. Sometimes this means doing what Ryskind calls "strengthening Reagan's conservative instincts." For weeks before the president released his budget, for example, the newspaper urged Reagan to reject advice from his aides. "Reagan Should Hold Firm to Tax-Cut Stance," said a typical headline from that period.

When Reagan did so, the newspaper proclaimed: "Reagan Reaffirms Conservative Course: Rebuffs Advisers on Taxes."

Most often the paper's advice takes the form of attacks on moderate Reagan appointees, or "nervous Nellie advisers." "Conservatives Find Administration Officers Undermining Reagan Mandate" blared one headline.

Reagan himself emerges from its pages as a well-meaning, true-blue conservative who would have easily set the world right by now if only he hadn't been sabotaged by misguided advisers.

The two advisers the newspaper finds the most worrisome are Secretary of State Alexander Haig and White House chief of staff James Baker III.

Haig originally was a Human Events favorite, but after a year in office it decided he was a "pure de'tentist" and "the wrong man for the job."

"The secretary loves to bluster about the Soviets, but when it comes to urging actions short of war, his advice is remarkably restrained," the newspaper declared Jan. 30.

Baker is another matter. He was suspect from the start, largely through guilt by association. Baker was George Bush's campaign manager during the 1980 primaries, and a delegate hunter for Gerald Ford in 1976.

Baker, who considers himself a conservative, is sensitive to criticism from the right, and has tried to woo Human Events writers and editors. He has impressed them as likable and capable, but Ryskind says, "I just don't know if his heart beats to the Reagan music . . . He is not reinforcing Reagan's conservative instincts."

The most pointed attack on the White House chief of staff and "the Baker network" came Jan. 23 from columnist E. Stanton Evans, who has been writing for Human Events for a quarter century.

"The administration of Ronald Reagan is close to being captured by moderate Republicans who opposed his presidential aspirations," Evans warned. "The White House staff itself is heavily tilted toward the followers of George Bush (and others of even more liberal persuasion) while the management of foreign policy is firmly in the grasp of those who came to power as acolytes of Henry Kissinger."

Evans went to some length to describe "the Baker network," including Richard G. Darman, "a follower of liberal GOPer Elliot Richardson," lobby chief Kenneth Duberstein, "a former aide to Sen. Jacob Javits," and Republican National Committee deputy chairman Richard Bond, "a former staffer for Sen. Charles Mathias of Maryland and assistant to Bush."

"It would be hard to imagine three appointments in more critical spots, drawn from sources more distant from the grass-roots conservatism that boosted Reagan to the presidency," said Evans.

Human Events' owners clearly enjoy thinking this kind of commentary is being read within the White House. But they aren't sure how much real influence they have within the administration.

The only direct example of a Human Events story influencing policy that they cite is one last fall headlined: "Humanties Dept. Bankrolling Leftist Democratic Network."

The article alleged Joseph E. Duffey, then chairman of the National Endowment for the Humanities, "has been busily shoveling hundreds of thousands of dollars into the coffers of the Democratic left."

Winter says Reagan read the front-page story and passed it on to aides with an angry note. Three weeks later, William Bennett was named as the new chairman of the agency.

Ironically, the Reagan administration has hurt, not helped, the newspaper's circulation. Winter is hoping that this will change and the newspaper has recently launched a circulation campaign.

But what can the president expect from his favorite newspaper?

"If Ronald Reagan sticks to his instincts, we won't be giving him fits all year," says Winter.