Abstract: A kind of chaotic synchronized secure communication scheme with time-varying parameters was proposed to solve the problem of parameter sensitivity reduction caused by chaotic synchronization, which further degrades the security. The stability of synchronization was then proved. It is unique that the chaotic activities obey the strange attractor globally, while in local they move randomly. As a result, the chaotic obits are more complex, the parameter sensitivity degree rises from 1 to 10. It makes the system hard to be broken by exhaustive attack and phase space restructuring. When the active-passive decomposition method is used, the secure communication scheme has no synchronized error. Simulation results indicate the effectiveness of the method. It is applicable to a kind of continuous chaotic system.