To improve the optimization speed of the Phasor Measurement Unit (PMU) and to use the minimum number of PMUs, combined with the characteristics of zero injection buses, an algorithm of a PMU placement method based on an integer programming algorithm is proposed. Looking at the observability of the whole power system, a mathematical model is established, and the characteristics of zero injection buses are considered. The optimal positions of PMUs are obtained by solving the system model. The IEEE 14-bus, IEEE 18-bus, IEEE 30-bus and IEEE 118-bus system are simulated, and the improved integer programming method proposed in this paper is verified by Matlab and Lingo tools. The constraint equation is optimized, and the position and quantity of PMUs are obtaind. Compared with integer programming, simulating anneal arithmetic and the improved genetic algorithm, this algorithm can effect the power system observability using fewer PMUs. The effectiveness and superiority of the proposed method are verified. This work is supported by the National Natural Science Foundation of China (No. 51967004).