Abstract: Due to the effects of the super El Nino during the dry season of 2016, all the countries in the Lancang-Mekong Basin suffered the drought disasters in various degrees, especially the Mekong Delta was struck by the most severe drought in the past hundred years. In this case, Chinese government decided to implement an emergency water supplement to the Mekong River in a 'three-phase plan' by increasing the water discharge from Yunnan's Jinghong Reservoir. In this study, the analysis covers flow propagation along the mainstream, and hydrological influence of the emergency water supplement in 2016 on the Mekong mainstream based on the water level and discharge data of hydrological stations on the Lancang-Mekong mainstream and meteorology data in the basin. It is found that the emergency water supplement from China increased water level and discharge along the Mekong mainstream, helping the drought mitigation in the Mekong basin countries.