Harvard professors know that it pays to work for a rich school, according to a study by the American Association of University Professors.

The association found that Harvard ranked first among Ivy League universities in the average salary it paid its full professors for the academic year 1984-1985: $62,900.

The average for the other seven Ivies was $11,200 less than Harvard. Full professors at second-place Yale average $55,800. Following Yale are Princeton, Columbia, Pennsylvania, Cornell, Dartmouth, and last-place Brown, whose scholars average a comparatively paltry $47,500 a year.

Maryse Eymonerie, who compiled a nationwide list of professor salaries for the Association's publication, Academe, said the numbers do not include professors' benefits.

Harvard Financial Vice President Thomas O'Brien, the university's top money-man, was out of town yesterday and unavailable for comment.

But at least one professor feels that money isn't the only thing.

Professor of Mathematics Benedict H. Gross, who defected from Brown last year, said the prospect of a bigger paycheck was not the reason. "Harvard pays more, but the cost of living in Cambridge--especially for housing--is much more than it is in Providence."

Asked for comment, Brown Associate Provost John Quinn said that "we have been close to the bottom of the Ivy League list for quite some time. For a number of years, we squeezed ahead of Dartmouth, but I guess we've slipped right past them again."