This paper investigated the effects of correlated noises on the signaltonoise ratio in a linear system with bias signalmodulated noise. By calculating the exponential of an integral of the noise, we obtained the expressions of the first moment,the correlated function and the signaltonoise ratio. The curves of signaltonoise ratio indicate that the additive noise can strengthen the signaltonoise ratio while the multiplicative noise decreases the signaltonoise ratio,and the correlation between the additive and multiplicative noise can increase the signaltonoise ratio.