Law-enforcement authorities from China, Laos, Myanmar and Thailand joined forces on Tuesday for the 101st Mekong River joint patrol.
According to the Yunnan Provincial Public Security Department, the vessels will navigate over 600 km over four days and three nights.
Before the patrol, the four countries' law-enforcement authorities held a video conference to discuss the river's security situation. They agreed to clamp down on illegal activities jointly.
The officers from the four countries have seized 11.85 tonnes of drugs and busted 11 criminal gangs since December 2011.
The Mekong River, known as the Lancang River in China, is a vital waterway for cross-border shipping.