The invention relates to a method for determining the risk propagation threshold of electric power CPS network based on seepage probability, which is characterized in that the electric power CPS network is abstracted into a directed unweighted graph of a two-layer complex network according to topological association and coupling logic, and are used for determining the risk propagation threshold ofelectric power CPS network based on seepage probability, a one-to-many and partially coupled inhomogeneous power CPS characterization model is established by using asymmetric balls-Into-bins distribution method; by Considering the directionality of the links between the information layer and the physical layer, the seepage probability is introduced to establish the propagation kinetics equation of the coupling relationship between the information layer and the physical layer; the risk propagation threshold is solved numerically by defining the survival function of power CPS network nodes. Itsolves the problem that the critical point of risk outbreak is difficult to determine numerically due to the non-uniformity of power CPS network and the dynamic process of risk propagation. The methodhas the advantages of scientific reasonableness, strong applicability and good effect.