Boris Becker, Wimbledon's 17-year-old champion, was given a hero's welcome today by a hometown crowd still enraptured by his stunning achievement last Sunday in becoming the youngest men's singles winner in tennis' most fabled tournament.

More than 25,000 people poured into the streets of Leimen in bright sunshine to cheer Becker as he was driven in a convoy to the town hall, where Mayor Herbert Ehrbar presented him with a ring of honor for his "model behavior and very special sporting accomplishment." The city's total population is 17,000.

Trappings of instant fame surrounded the red-haired hero: squealing teen-agers waving posters of their idol, street corner vendors hawking postcards and stamps bearing his visage, and a five-foot giant pretzel shaped in his double-barreled initials decorating the local tennis club where he learned the game.

While Becker has relaxed the past few days at his residence in Monaco, a burst of national pride has swept West Germany. In a year marked by controversy surrounding the 40th anniversary of the end of World War II and President Reagan's trip to the Bitburg cemetery, Germans have celebrated the victory of a new generation's tennis hero as a welcome tonic for painful political remembrances.

Newspapers have extolled him for giving the country a new cause for self-respect and irreproachable glory. The political weekly Die Zeit featured Becker in a contemplative lead article on the nature of hero worship, citing him for embodying the virtues of what Germans seemed to have lost: "joy in achievement, decisiveness and sheer unbounded self-confidence."

While noting that "identifying with a successful individual can be enriching" for the masses, the paper also alluded to the dangers of idolatry.

Casting a teen-age athletic champion as a political metaphor might be unfair, but even President Richard von Weizsaecker and Chancellor Helmut Kohl dispatched congratulatory telegrams.

Becker, a tennis professional for barely a year, seems destined to be the focus of a new industry as well as Germanic pride. He already is picking up close to $500,000 a year in equipment and clothing endorsements. Barber shops are advertising haircuts labeled the "Boris look." And "I love BB" T-shirts have become the fashion rage.

"We all know and like you as the modest boy next door," said the mayor in his speech today. "We have seen that success has not changed you and wish for the future that problems arising from such popularity will not harm you."

For the moment, Becker seems remarkably unaffected by the glare of success. He is carefully sheltered by his coach, Guenther Bosch, and his manager, Ion Tiriac, a Romanian who previously advised Ilie Nastase and Guillermo Vilas. His parents, who still live in Leimen, have remained in the background as he embarks on the globetrotting tennis circuit.

A spate of overnight biographies has released a torrent of trivia about his life, and the purported secrets of his success are being copied avidly by admirers. Becker's booming serve, clocked at 125 mph, has been attributed to eating granola for breakfast. His cool demeanor ostensibly derives from relaxation techniques: playing chess with his coach before every match and listening to Eric Clapton and Tina Turner on his Walkman.

As he accepted a golden ring from the mayor today and autographed the town's book of dignitaries beneath Henry Kissinger's signature, Becker sought to offer reassurances to his hometown fans that his exile in Monaco, for tax purposes, would not prevent him from maintaining contact with his roots.

He seemed overwhelmed by the reception. "I feel much better on a tennis court than I do on a speaker's rostrum," he said. "I can't believe there are so many tennis nuts in Leimen."