Based on the monthly runoff data of 53 years from the Shijiao Wtation in the Beijiang River Basin, the annual runoff distribution characteristics were studied, and several indices related to the attributes of uneven, concentrate degree and amplitude of variation were calculated. The results show that annual runoff distribution in 1950s and 1960 is uneven, after 1970s it becomes moderate than before, concentration period and minimum ratio change with fluctuation. From the tendency of each index, it shows that non-uniform coefficient, adjustment coefficient and maximum ratio changed in 1967, 1975 and 1999; concentration changed in 1999; concentrated period changed in 1984 and 1999; minimum ratio changed in 1975, 1983, 1991 and 1999. Variation in distribution trend of rainfall and runoff is not the same, trend of uneven characteristic of runoff distribution reduced than rainfall, delay time of runoff to precipitation increased, trend of maximum ratio of runoff decreased than rainfall, change of minimum ratio is smoother than rainfall. Annual distribution characteristics of runoff in the Beijiang River Basin have changed. Construction of water conservancy facilities within the watershed, soil erosion, economic development were analyzed. The result shows that the variation of annual runoff distribution in the Beijiang River Basin is mainly affected by the combination of the human activities.