In order to solve the lower voltage problem of low voltage rural network, a method for improving the voltage quality based on genetic algorithm to optimize the allocation of distributed photovoltaic power is proposed. Firstly, the network adjacency list of tree structured grid is established, the total load of each node is deduced, and the node voltage calculation method of each node before and after photovoltaic connected is obtained. Then the objective function and constraints are established. The objective function includes least allocation of distributed photovoltaic power capacity and node voltage deviation minimal. The constraint includes voltage deviation range, allocation capacity constraints. The optimization allocation method of distributed photovoltaic power based on genetic algorithm is constructed. And actual example is verified and analyzed. Simulated results show that the proposed method can improve the voltage deviation of each node in the network through the rational allocation of photovoltaic power without changing the grid structure and increasing the compensation equipment.