Abstract: In view of the current situation that it is difficult to comprehensively and quantitatively evaluate the complexity of geological structure, based on the statistical self-similarity of geological structure in terms of scale, structure, shape and mechanical characteristics, the development degree of geological structure is quantitatively studied by taking Qianjiaying Field of Kaiping Coal Field as the research area and using the fractal theory, and the fractal dimension is used to evaluate the complexity of geological structure quantitatively. The results show that the average fractal dimension value of the fold in Qianjiaying Field is 0.939 1, and the fold fractal dimension is high in the northeast, low in the middle and high in the southwest; the average fractal volume dimension of the fault is 1.454 4, and the fault mainly developed in the northeast. The fractal method can be used to obtain the structure distribution in the study area with the same accuracy as the result of mathematical geological trend surface analysis.