Abstract: It is important for rock engineering such as nuclear waste disposal, slope stability, mining engineering and hydropower project to describe quantitatively the distribution of geological faults. A distribution diagram of faults is obtained from the geological diagram at Zipingpu Hydropower Project. The data set of 126 faults at the site is analyzed statistically. The fault lengths are found to have a distribution of three orders of magnitudes. . A power-law relation between the fault number and the fault length is proposed, i.e., N(r)~r-D. Two power exponents are estimated by using linear fit in two segments. It is found that the power exponent has a value of 0.32 if faslt lengths are shorter than 2.5km. The power exponent is equal to 1.58 if fault lengths are longer than 2.5 km. It is suggested that the power-law relation between fault number and fault length is of a significant importance for extrapolation of a fault distribution to either further small or further large scales.