In order to meet the need of chaotic secure communication, a scheme of generating high quality chaotic optical signals by mutually coupled semiconductor ring lasers was proposed. The time series, power spectrum and autocorrelation coefficient distributions under various parameters were obtained by numerical simulation，and the theoretical analysis was carried out. The results show that under certain parameters, the laser can exhibit single-period, multi-period and chaotic dynamic states. In the case of large frequency detuning, the delay characteristics of chaos are well suppressed. By scanning injection parameters in a wide range, the chaotic signal with a maximum bandwidth of 14.0GHz and a low time delay signature can be obtained, which can significantly improve the transmission rate and security of chaotic secure communication. The results of this paper can provide some theoretical reference for the application of ring laser in chaotic secure communication.