China has set a target of four gold medals at the upcoming World Swimming Championships in Barcelona, Spain, said head coach Yao Zhengjie on Tuesday.

"According to our results this year and the world rankings, I hope we can claim four golds at the Barcelona Worlds, as we have four world fastest times in the year," Yao said.

China unveiled on Tuesday its 48-swimmer squad for the Barcelona Worlds, with Olympic and world champions Sun Yang and Ye Shiwen spearheading their assault.

Sun, who grabbed two golds at last year's Olympics in London, ranked first in both men's 400m and 1,500m freestyle, while Jiao Liuyang, winner of the women's 200m butterfly at the London Games, had the world fastest time for her specialty. Fu Yuanhui, 17, set the world fastest time in women's 50m backstroke.

"We had very good results at the London Games, but it will be hard for us to repeat the feat in Barcelona, as the weather, the food, and the atmosphere in Spain would be problems for us," said Yao, who steered Chinese swimmers to a harvest of five golds at London 2012.

Sun, who fell out with long time mentor Zhu Zhigen early this year and trained seperately, arrived in Beijing on Tuesday to join the training camp.

"I feel good," said Sun, who just ended a two-week training session in Hong Kong under the guidance of former Chinese head coach Zhang Yadong.

"The new environment and new coach gave me a new start," added the 22-year old.

"I trained well in Hong Kong and I am on the right track now. If everything is right, I think I can win the 1,500m free."

Sun will take part in the 400m, 800m and 1,500m freestyle as well as the men's 4x200m freestyle relay at the Worlds.

The Chinese swimming team will leave for Barcelona on July 23.