A new approach of chaotic modulation and linear demodulation for secure communication is proposed.The transmitter and the receiver have the same chaotic circuit respectively.An information signal is introduced into the linear subcircuit of the chaotic circuit in the transmitter to modulate the chaotic circuit.One of the chaotic signals modulated is transmitted to the chaotic circuit of the receiver.A certain current or voltage variable in the chaotic circuit of the receiver is detected and demodulated by a linear filter and the information signal can be recovered.The chaotic communication system based on the new modulating and demodulating approach is highly secure and simple in circuit.The simulation results of two secure communication systems designed by this approach are quite satisfactory.