This paper presents a new method of chaotic communicaion based on multistage Chua' s circuits with time - varying channel gain. In this method , the variation of channel gain is attributed to an equivalent .time - varying resistor that exists in channel. Here , this resistor is regarded as coupling resistor between two Chua's circuits. At receiving end , chaos synchronization of transmitting and receiving system is judged by using current in channel.Simulation results show that chaos synchronization of two Chua's circuits can be achieved when the channel is in time - varying gain. Then a multistage chaotic synchronized system for secure communication with time - varying channel gain is given by using parameter modulation.