Using the linear approximation method, the intensity fluctuation of the optical bistable system driven by both the colored pump noise and colored quantum noise with cross-correlation was calculated, and the influence of intensity of noise and its cross-correlation form on intensity fluctuation was discussed. It’s found that there is a minimum of the intensity fluctuation when the intensity of the pump noise and the quantum noise change, and it is closely related to the cross-correlation of the noises, but the input signal has little effect on the intensity fluctuation.