Abstract: The irrigation canal system can be viewed as a fractal with fractal dimension, and the part of canal system composes the information of the whole system on a certain degree. In this paper, the fractal theory is introduced to the research of irrigation canal system to analyse their fractal characteristics and the fractal dimension. The box-counting algorithm is adopted to calculate the fractal dimension of irrigation canal system in Zhanghe Irrigation District. Based on those studies, the correlation between the fractal dimension and irrigation modulus is testified, which could provide some theoretical bases for the optimal layout of irrigation canal system.