With the development of power and information technology, the impact of network attacks on the power infrastructure has gradually become a hot issue at home and abroad. In order to measure the risk caused by network attack to power facilities, this paper proposes a risk assessment model for distribution network considering network attack. In this paper, firstly, the definition of attack object, network attack pattern and attack consequence are defined. Secondly, the risk assessment index of distribution network is put forward. And then, Monte Carlo method is used to simulate the network attack scene, that is, attack the elements in the target component set with a certain probability. Finally, the risk index of distribution network is calculated by the proposed evaluation model, and the risk assessment of distribution network is completed. The proposed model can deeply reveal the security level of power grid under network attack. The validity and feasibility of the proposed method are verified by an example of IEEE-33 node distribution system.