This paper proposes a fast assessment method of the photovoltaic capacity that can be absorbed by the distribution lines in the station area with voltage as the constraint condition. The problem of voltage overload of the distribution line in the station area is solved. This method analyzes the change of line voltage when photovoltaic power is connected and establishes an evaluation model of its maximum capacity. The main parameter of this model is the sensitivity coefficient. The sensitivity coefficient of each line parameter is calculated, and then the influence of maximum capacity on each line parameter is obtained by using multiple linear regression method. The influence of capacity on the parameters of each line can be predicted to a certain extent by judging whether the line is heavily overloaded or not. Finally, experiments on the Huxi Tower Yuangong Substation and the Huxi Zhonggetian Platform verify the effectiveness of the proposed model.