Due to the severe intermittence, volatility and uncertainty of the output power, the integration of large scale photovoltaics (PVs) will have a great influence on the power flow and node voltage of a distribution network, causing the operation risk of distribution network. This paper researches the risk assessment method and countermeasures for distribution networks with large-scale PV accessing. Based on the risk assessment indexes of node voltage limit violation and line power flow limit violation, a distribution network operation risk assessment model is established, the specific implementation steps of the risk assessment method are presented, and specific risk countermeasures are proposed. Examples of the risk assessment method proposed in this paper is illustrated, and the effectiveness of the risk countermeasures are verified by simulation results.