QINGDAO - Olympic champion Sun Yang fired off his personal-best 1,500m freestyle in four years and collected his fourth title on the last day of the Chinese Swimming National Championships here on Sunday.

Sun, who stormed three world-best time this season in 200m, 400m and 800m, led the field to win the the 1,500m freestyle in 14 minutes 55.00 seconds, his personal-best since 2015.

Ji Xinjie came to second in 15:03.38 and Cheng Long third in 15:10.80.

"It was the event I felt the most satisfied among all the four events I have competed. I beat the barrier of 15-minute and clocked my best time in four years since I changed my focus to the middle distance after 2012 Olympic Games," said the 27-year-old, the eldest one at the meet.

"I was so excited and happy because I found back my endurance for this marathon event and felt more confident in the mid-long distance events," Sun said.