Abstract: The separation-time of system variable can reflect the approximate level of system parameters in the chaotic system, this facilitates parameters detection and synchronizating attack. For soluting this security weaknesses of all the chaos system we got a new chaotic variable by preprocessing the chaotic variable and adding disturbance to the system parameters. The separation-time of new variable can't reflect the approximate level of system parameters almost. Subsequently, a self-synchronization chaotic encryption method with time-varying keys was presented. This method can re- sist the synchronizating attack and has the capability of one time padding. Security analysis and simulation results show that method is feasibly and safety.

Key words: Chaotic, Encryption, Time-varying keys, Security