Fractal theory was applied to analyze grain size distribution of the sediment of Weihe River in Xianyang City.The fractal scaleless range and the fractal dimension of grain size distribution were determined.In the non-scaled range,the correlation coefficients(R2) of 53 samples were all higher than 0.95 and the average fractal dimension was 2.12,which shows that the distribution of sediment particle size exhibited good fractal characteristics.The fractal dimension as a new parameter of sediment grain size analysis was compared with traditional granularity index such as mean-diameter(Φ),standard deviation(σ),skewness and kurtosis.The correlation coefficients of fractal dimension of sediment grain size with mean diameter,standard deviation,kurtosis and skewness are 0.807,0.707,0.675,and 0.112,respectively,implying fractal dimension correlated significantly positively with mean diameter,standard deviation and kurtosis,but insignificantly positively with skewness.