In order to reveal the impact of forest coverage on runoff of the basin in the Loess Plateau of China, multi- year observational data were collected from 53 basins located in a typical loess area of the Loess Plateau of China. The impact was investigated using trend analysis, regression fitting, and serial cluster analysis. The results showed that 25% forest coverage is the partition point impacting the mean annual runoff coefficient, dividing the basins into two groups with forest coverage <25% and forest coverage ≥25%. For the former, the correlation between forest coverage and the mean annual runoff coefficient is very weak, while for the latter, the correlations conform to negative exponential function, the correlation is significantly negative at 0.01 level and the correlation coefficient is 0.614, and forest coverage has a relatively large impact on the mean annual runoff coefficient and that the mean annual runoff coefficient decreases significantly as forest coverage increases. Therefore, revegetation within 25% forest coverage will not have a large impact on local water resources, and the results provide some reference for revegetation in areas of the Loess Plateau of China.