On the basis of typical optoelectronic oscillator (OEO) chaotic system, the output of chaotic laser is fed back to the Mach-Zehnder modulator (MZM), so that the gain coefficients of the original system can change dynamically and a second time delay is introduced into the system. Then we study the effects of the feedback time and the feedback intensity of the improved chaotic system on the time-delay characteristics and complexity of the system theoretically. The simulation results show that the chaotic laser generated by the optoelectronic oscillator with optical feedback has higher complexity and lower delay characteristics. The system exhibits the better chaotic dynamic characteristics when the delay time of the optical feedback is the same as the delay time of the photoelectric delay. The results show that this method can produce more complex chaotic signals and reduce the delay characteristics of signals without increasing the system costs, and it is helpful to improve the security of the system.