Chinese swimmer Sun Yang will return to the pool at a major domestic meet next week following the expiry of his four-year ban for doping.

State media reports Sun, China's first Olympic gold medallist in men's swimming, will represent his home Zhejiang province at the National Summer Swimming Championships which start on Sunday in Hefei.

Wang Wei, director of the Zhejiang Provincial Swimming Sports Management Centre, said the 32-year-old will compete in the 400m freestyle, the event he won at the 2012 London Olympics, according to Xinhua news agency.

The triple Olympic champion was banned from competition for four years and three months for a dope test violation in 2018 in which he and members of his entourage smashed vials containing blood samples.

The ban, reduced from eight years on appeal, expired on May 28.

While suspended, Sun missed national trials for the Paris Olympics where China's swim team were under intense scrutiny over the country's doping record.

The World Anti-Doping Agency (WADA) confirmed reports in April that 23 of the nation's swimmers tested positive for trimetazidine, a heart medication banned under the WADA code, in the lead up to the Tokyo Games.

WADA accepted the findings of a Chinese investigation that the test results were due to contamination from a hotel kitchen the team were staying at.

Sun served a three-month suspension in 2014 for taking trimetazidine, which he said was to treat a heart condition.

The meet in Hefei is second only to China's National Swimming Championships in terms of competitive level and prestige, said Xinhua.

Though Sun is cleared for competition he may have little chance of swimming for China again.

Chinese athletes who receive doping suspensions longer than a year are banned from national teams, according to the country's anti-doping rules.

China won 12 medals from the pool in Paris, including two golds.

Pan Zhanle claimed the men's 100 freestyle title in a world record time, while China won the men's 4x100 medley relay gold, ending the United States' unbeaten record in the event.

Xinhua said Pan and provincial teammate Wang Shun, the former Olympic champion who took bronze in the men's 200 individual medley in Paris, were not included in Zhejiang's team for the Hefei meet.