Abstract: Network-connected distributed generation(DG) brings a series of impacts on distribution network, in the trend of a large number of distributed generations that mainly formed of wind energy and photovoltaic power generation integrate in grid, so it is of importance to study the bearable DG capacity of a distribution system under the tendency that a lot of DGs urgently need to be connected. In this paper, taking full voltage fluctuation index and limited short-circuit capacity into account under the premise of considering static security and power output of distributed generation, an optimization model whose objective function is maximum capacity of distributed power is promoted. Genetic algorithm is selected to solve the model of penetration capacity calculation for multiple distributed generations, because it is simple, easy to use, and suitable for parallel computing. Through the simulation of IEEE 33-nodes system, the effects of different types of distributed power and limited distribution network capacity are analyzed and the maximum limited capacity boundaries considering of different combinations of distributed fans and photovoltaic are given in the paper, so the effectiveness and correctness of the proposed model are verified.