The invention relates to a reactive compensation method based on the improved differential evolutionary algorithm and applied to an electric power system with wind power plants. The reactive compensation method based on the improved differential evolutionary algorithm and applied to the electric power system with the wind power plants comprises the steps that load flow calculation is conducted, a set proportion of nodes with the smallest reactive margin values and nodes with voltages lower than a set value Ulimit in the system are selected to serve as nodes to be compensated; an objective function is established, and an initial population is generated; mutation, crossing and selection are conducted on individuals in the initial population according to the evolutionary algorithm until the number of iterations or the adaptability of individuals in the updated offspring population reaches a set optimal objective function value. According to the reactive compensation method based on the improved differential evolutionary algorithm and applied to the electric power system with the wind power plants, the reactive compensation point and the reactive compensation capacity can be determined reasonably, both the comprehensive optimization of the compensation effect and the voltage stabilizing effect is achieved, and thus safe and reliable operation of the electric power system with the wind power plants is promoted.