The official Xinhua news agency described the manoeuvres as routine, but they come as China is engaged in an increasingly bitter, high stakes dispute over maritime territory with Japan and with several Southeast Asia nations.
"The fleet will carry out more than 20 types of exercises including naval confrontation, battle drills far out at sea, the protection of maritime rights and command and control," Xinhua cited the Defence Ministry as saying in a statement.
"These exercises on the high seas will take in the Yellow Sea, the East China Sea, the South China Sea, the Miyako Strait, the Bashi Channel and the seas to the east of Taiwan."
President Hu Jintao has made boosting the navy a priority, especially in trying to turn it into a blue-water fleet able to operate far from China's shore, and Chinese ships have participated in anti-piracy missions off Somalia.
But China's growing defence budget, military advances and perceived lack of transparency have alarmed its neighbours and the United States. China is developing stealth fighters and last year launched its first aircraft carrier.
On Sunday, the government said it had again tested emerging military technology aimed at destroying missiles in mid-air.
China says it has no hostile designs and that it is simply updating its outdated forces.
The Pacific drills are "a normal way of exercising to raise the fighting ability of the navy", Xinhua cited a naval officer as saying, adding that it was common for other navies to drill in seas far from home.