in order to deeply understand working priciple of cochlea. influences of motion of basilar membrane on resolving power for different frequencies and sound pressure levels were studied. because the original model for vibration of basilar membrane didn't consider influences caused by different moving speeds of outer hair cells in the course of their own motion on frequnency response of basilar membrane, it could not completely describe active respnance effect of outer hair cells. therefore, time-delay characteristic of outer hair cells in mechanical process of incereasing frequency selectivety of basilar membrane was induced. according to results of simulation calculation, the corrected model absolutely accorded with physiological features of mechanism of action of outer hair cells and it explained the effect of outer hair cells's motion on viration of basilar membrane.