According to the Yunnan provincial public security department, 128 law enforcement officers participated in the mission aboard six vessels, covering 542km.
A consultation meeting on emergency response capability was also held in Laos.
As planned, China and Laos will hold a week-long training session in key areas on the Mekong River following the patrol.
Joint patrol among China, Laos, Myanmar and Thailand began in late 2011 after a gang hijacked two vessels and killed 13 Chinese sailors on Thailand’s waters.
The Mekong River is a vital waterway for cross-border shipping among China, Laos, Myanmar, Thailand, Cambodia and Vietnam.