In this paper, the method of synchronizing chaos by driving of discrete chaotic system in continuous chaotic systems is proposed. The logistic map, Henon map and the system of Lorenz are taken as three typical examples. The simulation results show that two continuous chaotic systems can be synchronized completely when the strength of the driving signal is large enough and the spectrum of the output signal is similar to the spectrum of white noise. At the sametime, we have studied the possibility of secrete communication based on the method proposed in this paper.