For the two schemes of classical-quantum signals simultaneous transmission sharing a same fiber-transmission in the same waveband and transmission in distant wavebands, the formulas for calculating the counting rate of spontaneous Raman scattering noise are derived respectively. Based on this, the influence of classical launch power and transmission distance on performance quantum key distribution is analyzed. The simulation results show that the counting rate of spontaneous Raman scattering noise in the same waveband is greater than that in distant wavebands under the same classical launch power. As the classical launch power increases, the slope of counting rate of spontaneous Raman scattering noise in the same waveband is much higher than that in distant wavebands. The quantum key distribution performance of the two schemes is affected both by the classical launch power and transmission distance. It ′ s more suitable to adopt the scheme of transmission in distant wavebands when the classical launch power is at high level and transmission distance is not so far. Conversely, it ′ s more suitable to adopt the scheme of transmission in the same waveband when the classical launch power signal is at low level and transmission distance is great.