Abstract: In order to study characteristics of a laser system, the signal-to-noise ratio (SNR) of the output laser intensity for a single mode laser was analyzed theoretically by means of linear approximation based on the loss model for a single mode laser driven by the colored pump noise and quantum noise with correlation of the real and imaginary parts. Then, effects of amplitude, low frequency of modulation signal, high frequency of carrier signal, intensity of quantum and pump noise, correlation coefficient of quantum noise between the real and imaginary parts on stochastic resonance of a laser system were analyzed in detail. It is found that the SNR has stochastic resonance phenomenon because of the net gain coefficient of the laser system. The result will provide some theoretical basis to optimize laser dynamics.