The invention discloses a power communication backbone network safety risk assessment method based on network topology. The method comprises the following steps of: identifying a network unit in a power communication backbone network topology chart; respectively calculating the service importance and safety risk event probability of the network unit; and respectively calculating safety risk values of the network unit and the link and performing risk assessment. The safety risk assessment of the power communication backbone network is performed by combining the network topology and the network service importance, the network and link in the backbone network are subjected to safety risk assessment, the safety risk level of the whole backbone network can be counted, the assessment result is specific and credible, the actual field requirements can be met, and the method is convenient for management of managers and has practical guiding significance.