A method for characterizing the pore network structure of a coal rock comprises the following steps: obtaining three-dimensional data of a coal rock core pore structure by a CT technology, establishing a three-dimensional digital rock core, and establishing a three-dimensional pore network by using a central axis algorithm; simplifying the model data of the pore network, simplifying pores into nodes, simplifying pore passages into edges, marking the pores, and deriving pore communication information; and using a complex network to characterize the basic information of the network, comprising the total number of the nodes, the total number of the edges, node distribution, the average degree of the nodes, the average path length of the network, the network clustering coefficient, the networkmedia, the network density and the network robustness. Compared with traditional coal rock pore structure analysis methods, the method in the invention increases network property analysis, can analyze the seepage law of different pore network communication structures having the same porosity to achieve the purpose of improving the existing gas recovery rate at the microscopic level, and adopts acomplex network theory to quantitatively characterize the pore structure network parameters of the coal rock in order to accurately and comprehensively characterize the pore network communication property of the coal rock.