The fleet departed Tuesday from a military port in the eastern city of Qingdao, carrying three helicopters.
The three ships are missile destroyer Qingdao and missile frigates Yantai and Yancheng, all from the North China Sea Fleet under the PLA Navy.
During the voyage, the fleet will conduct multi-programme training sessions in the sea areas where China has been carrying out regular patrols.
It will conduct more than 20 types of exercises, including maritime confrontation, open-sea mobile combat, law enforcement missions and open-sea naval commanding.
Fleet commander Tian Zhong told Xinhua that conducting training in international waters was a normal practice among various navies around the world.
It will also help improve the PLA Navy's combat capabilities, he said.
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The training area will include the Yellow, East China and South China seas, the Miyako Strait, the Bashi Channel and the sea area east of Taiwan.
On Tuesday, as part of the ongoing open-sea training, the fleet held a four-hour maritime confrontation drill in the Yellow Sea with another PLA Navy fleet set to depart for escort missions in sea areas off Somalia.
The Qingdao, which is among China's second-generation missile destroyers, was commissioned in 1993 and has taken part in more than 50 missions, including escort missions in the Gulf of Aden. It has a displacement of 4,800 tonnes.
In 2002, the vessel completed the PLA Navy's first global voyage.
The Yantai and Yancheng, among China's newest type of missile frigates, were commissioned by the North China Sea Fleet in 2011 and 2012 respectively. They both have a displacement of 4,050 tonnes.
The navy conducted seven similar training exercises last year.