In order to enhance the security and meet the real-time confidential communication requirement of important power information in smart grid，a novel power information encryption method is proposed based on optimal coordinated composite chaotic cryptosystem.The composite chaotic system is constructed using two one-dimensional chaotic systems with good initial value sensitivity，good pseudo randomness and aperiodicity.The wavelet coefficients of plaintext are encrypted by using composite chaotic block sequences in wavelet transform domain.According to Shannons cipher theory，correlation coefficient and uniformity indices are selected to form the comprehensive objective function.A new adaptive chaotic immune particle swarm optimization algorithm based on the idea of chaos optimization and artificial immune is presented and applied to design optimal coordinated parameters of the composite chaotic system，which can strengthen the coordination between chaotic motion systems and improve the encryption performance of the composite chaotic system.Comparative encryption experiments，statistical analysis and sensitivity test results show that the proposed encryption method is feasible and effective.