Abstract: The randomly distributed fracture network in coal body is the main flow channel of coalbed methane, and the key to study the flow characteristics of coalbed methane is to accurately simulate the complex fracture network in coal body. Based on the pixel probability decomposition theory, a new discrete fracture network modeling method is introduced. Compared with the traditional method, which assumes that the fracture is a smooth fracture, this method can fully consider the rough characteristics of the fracture. Combined with numerical simulation, the influence of different fracture characteristic parameters on the permeability of the coal seam is analyzed. The results show that the porosity (0.1-0.25), fractal dimension (1.55-1.85), maximum fracture length (0.011-0.026 m) and proportion coefficient (0.006~0.08) have a good power-law growth relationship with the outlet velocity of the fracture network, while the tortuosity fractal dimension (1.0-1.02), fracture dip angle (10°-85°) and the outlet velocity of the fracture network have a power-law decrease relationship; among them, the proportion coefficient, fracture dip angle and maximum fracture length have the most significant effects on the outlet velocity of fracture network.