None of the 922 tests on 456 swimmers, both in and out of competition, turned out positive, according to officials.
"The number of tests rose 4.1 percent compared to last year and the number of Chinese swimmers taking the tests accounted for 35.84 percent of the total registered," national swimming administration director Li Hua told China Daily.
China has pledged to keep its swimmers clean ahead of the Beijing 2008 Olympics after outstanding international results in the 1990s were repeatedly followed by doping scandals implicating coaches and officials.
Stanczyk given belated gold
China's crackdown on drug cheats in recent years has been accompanied by less spectacular achievements in the pool.
Chinese swimmers reaped only one gold from the last two Olympic Games at Sydney in 2000 and Athens four years later, and failed to win a title at March's world championships in Melbourne.
Mellouli stripped of title
Mellouli could lose title