Ning Zetao of Henan reacts after the men's 100m freestyle swimming final at 13th Chinese National Games in north China's Tianjin Municipality, Sept. 4, 2017. Ning Zetao claimed the title with 47.92 seconds. (Xinhua/Ding Xu)

BEIJING, March 6 (Xinhua) -- China's star swimmer Ning Zetao, who made history to win the men's 100m freestyle at the 2015 Kazan Swimming World Championships, announced retirement on his Sina Weibo account here on Wednesday.

Ning celebrated his 26th birthday Wednesday on Weibo, twitter-like microblog, saying "to say goodbye to swimming pool and start my new life. The way to success is never easy, push yourself and do not settle."

Ning jumped to fame at the 2014 Asian Games in Incheon, South Korea, where he won four freestyle gold medals and made a perfect international debut. And then the Henan province native made a breakthrough victory at the 2015 Kazan worlds. His 100m free gold medal marked a milestone achievement in the Chinese swimming history, as prior to Ning's victory, no Asian swimmer had ever advanced to the final or won medals in this event at the World Championships.

After Kazan, Ning became famous with his fans going crazy for his good results and handsome physique. By now He owns 7.9 million fans in Sina Weibo.

However his competitiveness had been questioned as it seemed two many commercial activities prevented him from concentration on training and competition.

He failed to make the 100m final at the 2016 Rio Games and he was later expelled from the national squad for violating relevant commercial promotion rules.

Ning was not qualified for the 2017 World Championships and the 2018 Asiad in Indonesia.