The relationship between forest and water resources has been a main scientific issue in the study of ecological hydrology, which is also an important theoretic foundation for hydrological prediction and regulation. Different forest vegetations create different canopy structure and micro-environment, which affect the distribution of rainfall among canopy, litter and different soil layers through water interception, water retention and transpiration and exert a great impact on surface runoff and river discharge. Recent studies have showed that the function of forest vegetation in reducing flood peaks during the rainy season and increasing the river flow in the dry season might be exaggerated. The relationship between forest vegetation and river flow still needs further confirmation. Lijiang River was a core mountain-water scenic spot in Guilin. Precipitation in Lijiang river basin was abundant, but its distribution within the year was irregular and rainfall mainly happened in rainy season (from March to August). Forest vegetation in the basin plays an important ecological and hydrological regulating function. In this research, data was collected in typical forest vegetation in upper reaches of Lijiang River in Mao'er Mountain National Nature Reserve, Guangxi Province. Hydrological processes, such as rainfall, surface runoff and river flow were monitored and analyzed in typical forests of Mao'er Mountain. The results showed that, 1)The distribution of annual and inter-annual precipitation was irregular revealed by statistical analysis of annual precipitation. The rainfall intensity and the rainfall frequency in the rainy season were heavy and the rainfall in the dry season (from September to February of the following year) accounts for only 17.61% of the annual total precipitation.No significant trend was found for inter-annual precipitation in the last 50 years. The canopy interception was greatly related with rainfall characteristics and forest vegetation. 2)Forest ecosystems had complex canopy structure and exerted a great impact on rainfall redistribution and the average lag time of surface runoff was 70 min. With continuous rainfall, the lagging effect might not be obvious and the surface runoff and the rainfall appeared at the same time, which largely increased the probability of generating heavy runoff after light rain and also the risk of flood in rainy season. 3)The runoff coefficient in dry season was lower than that in rainy season because of less rainfall and more evapo-transpiration, which increased the risk of serious drought. Forest vegetation put off the peak of river flow behind, extended the runoff duration for 24 days with 18 days of continuous rainfall. For a long time, due to the different geographical environment, soil conditions and forest structure has different influence on the redistribution of precipitation, the formation process of surface runoff, underground runoff as well as evaporation, which lead to the relationships of forest vegetation, surface runoff, and river flow are still controversial in the academia. This study would provide scientific basis for better understanding of the relationships between forest vegetation and its hydrological effects, helping to facilitate water resources and achieving wise forest management in upper reaches of Lijiang River.