Based on monthly rainfall and runoff data from 1970 to 2014 at Zhangjiashan hydrological station of Jinghe River, the paper introduced Lorenz curve to calculate Gini coefficient and Lorenz asymmetry coefficient of runoff and precipitation by using Mann-Kendall method to carry out trend analysis and test.The results showed that annual runoff and rainfall displayed a falling trend from 1970 to 2014, but the downward trend of annual rainfall was not obvious.The average Gini coefficient of runoff and precipitation are 0.442 and 0.513 respectively;the annual proportion of Lorenz asymmetry coefficient of greater than 1 is about 75% and 20%respectively. The Gini coefficient of annual runoff showed decreasing trend and Lorenz asymmetry coefficient showed increasing trend, while both Gini coefficient and Lorenz asymmetry coefficient of annual precipitation appeared increasing trend.Therefore, the runoff distribution appears uniform and the percentage of month with large runoff volume increase; the uneven of precipitation distribution is strengthen because of the month of less precipitation.