A new chaotic system and secure communication method are proposed based on optoelectronic feedback device with variable parameters, because the present system is easily attacked by the method of parameter estimation so as to affect the security of the communication. Dynamical changes of the gain coefficient of the second-class system are generated by changing the injected light intensity through the output of the first-class system, which increases the number of controllable parameters in the system. The chaotic dynamics of the system are theoretically and numerically analyzed. The communication situation of the system in the chaotic modulation conditions and the chaos synchronization when the parameters including gain coefficient and time delay are not compatible is analyzed. The experimental results show that this scheme can increase the chaotic complexity, and can achieve the chaotic secure communication.