Aiming at the problem that the flexible access of distributed photovoltaics to the distribution network affects its reliability, this paper establishes a model of the distributed photovoltaic output probability based on the typical output characteristics of distributed photovoltaics firstly. Subsequently, the power grid risk assessment indicators are determined to facilitate the quantification of distribution network risks, including voltage over-limit, power over-limit, and load loss risk indicators. Finally, a distribution network model containing distributed photovoltaic grid-connected is established on the MATLAB simulation platform, and the risk assessment of the distribution network containing distributed photovoltaic grid-connected is carried out.