A highly robust chaotic synchronization scheme is proposed in this paper. Different from most synchronization scheme, the two continuous chaotic systems is not driven by each other, but the separated standard digital chaotic systems. Since the digital chaotic systems are not affected by the internal noise and external noise, our synchronization scheme is much more robust than other synchronization schemes. Based on this synchronization scheme, a chaos-based secure communication system is designed. We use return-map and spectrum to analyze the security of our system. Simulation results shows that our system is highly security.