According to the characteristic of voltage and reactive power optimization problem and the applicability of the immune genetic algorithm in solving global optimization problems, this paper applies immune genetic algorithm for voltage reactive power optimization system. It adopts the hybrid coding form when encodes and normalizes the similarity of antibodies, and takes transformation of fitness function in the choice of operation. The reasonable choice of transform coefficient value can maintain the population diversity algorithm in the early stage of the evolution and can still have a faster convergence speed in the late evolution. And it takes different measures in real number and integer gene in crossover and mutation. Taking the standard IEEE-30 node system for example and using optimization procedures to make reactive power optimization calculation, this paper verifies the proposed method has advantages in computing and convergence capabilities compared with other algorithms.