PRINCETON, N.J.--Harvard alumni from the class of 1957 oppose President Reagan's economic policies in greater numbers and are more likely to follow careers in medicine and education than their counterparts from Princeton and Yale, a survey of the classes of 1957 of the three institutions reveals.

The informal 148-question poll, conducted by mail for the Princeton Class of 1957's 25th reunion next summer, found Princeton's 25-year alumni make more money than those of Harvard or Yale, and are more likely to be brokers, manufacturers and government employees, the Daily Princetonian reported two weeks ago.

The average income of all respondents fell between $50,000 and $75,000, and 17 percent had assets worth more than $1 million. But while 27 per cent of Princeton alumni surveyed reported an income over $100,000, only 21 per cent of Yale respondents and 22 per cent of Harvard respondents had incomes above this level.

Forty per cent of the alumni responded to the survey, which shows Yale's class of 1957 to have the highest percentage of lawyers, salesmen and engineers.

Fifty per cent of both Yale and Princeton graduates agree with the Reagan administration's economic policies, while Harvard alumni registered only 34 per cent approval.

The political affiliation of both Princeton and Yale was considerably more Republican--45 and 58 per cent respectively--than Harvard, which split evenly between Democrats and Republicans.

Harvard respondents came largely from public schools (57 per cent), while 59 per cent of Yale and 51 per cent of Princeton alumni attended private schools.

Even with these apparent differences, however, Jack L. Goodman Princeton '57 and publisher of the 25th Reunion Book, said, "It is quite remarkable that we are all so alike despite attending different schools."