Bill Rodgers, the defending champion, will lead a field of 4,000 from 27 states, Canada, Mexico and New Zealand in today's 10-mile Perrier Cherry Blossom Run.

The race will start at 8:30 a.m. at Ohio Drive near the Lincoln Memorial, then wind around Hains Point and the Tidal Basin. There were 12,000 entries; a lottery determined the final field. Race organizers are calling this the best field yet and expect Rodgers' record of 48 minutes, set last year, to be broken. There are 30 runners entered who have gone the distance in 50 minutes or less, and 12 who have done it in less than 49.

"The (Olympic) trials are down the tubes, so everyone is coming here. We've always done well because we're two weeks before Boston," said Jeff Darman," the race's communications director, "and people use this as their last training run."

Rodgers, who won the Cherry Blossom in 1978 and '79, had a choice of two races this weekend. He passed up the 10-kilometer event in New York City to come to Washington, he said, because, "I think that it would be a better prep for the Boston marathon (April 21). The longer distance will help."

Rodgers said the torn muscle in his left calf, which had bothered him in January and February, is "basically better.For the last six weeks, I've been running 130-140 miles a week but when I push in on it, I can still feel it."

Rodgers would have been a favorite to win a gold medal at the Olympics this summer. Now he seems resigned to President Carter's boycott, though he doesn't like it. Reached by telephone at his Boston running store, Rodgers spoke out against the Olympic boycott.

"I don't know where to begin," he said."I'm against it, I'll tell you that. And I've been against it from the beginning.

"I notice more and more Americans are against it. Its easy for Carter to stand firm on this, its like taking candy from a baby. The athletes have no money, or lawyers, and its an easy way to push us around. I think its a bad policy decision."

Two of Rodgers' main competitors, John Flora and Bobby Hodge, also are coming from Boston for today's race. Flora was second in last year's Cherry Blossom and Hodge was third in the Boston marathon.

Kirk Pfeffer of Boulder, Colo., second in last year's New York City Marathon as a surprise entry, also is a surprise entry today. He and Dean Mathews of Clemson, winner of the 1979 Honolulu marathon, are other leading contenders.

Pfeffer lost the New York Marathon lead to Rodgers at 23 1/2 miles into the race.

"I read a comment where he said that I would never beat him again," said Rodgers. "He beat me in Las Vegas, where he set a record for the half-marathon. But I'm in a little better shape. He may beat me. Somebody may beat both of us. It'll be a good race."

Dan Rincon of Wheaton, winner of the 1977 Cherry Blossom, has entered along with Bruce Robinson of Silver Spring, a highly regarded marathon man. a

In the women's division, Jenifer White of Alexandria, the 1978 winner, is the favorite. Her competition will come from Anne Sullivan of Brown University; Pia Palladina of Georgetown University, and Marge Rosasco of Baltimore.