Aimed atthe stream flow cut-off of Weihe river basin at Huaxian station,it is importantthatthe runoff trend and influence factors are analyzed in this area. According to the data of runoff in Weihe river basin from 1956 to 2000,the changing trend of runoff at Huaxian station is analyzed by using the R/S analysis (Rescale Range Analysis). At the same time,the influence factors of runoff are analyzed. Results show thatthe H urstcoefficientis 0. 778 4,showing thatthe runoff trend is on the persistentdecline. The annual average runoff had been reduced by 3. 79×10⁹m³ from 1970 to 2000,compared to the runoff from 1956 to 1969. Among the influence factors,the reduction influenced by climate is 1. 96×10⁹m³ and the reduction influenced by human activities is 1. 83×109m³,amounting for 51. 7% and 48. 3% of the total reduction,respectively.