Objective Studying the accuracy of the traditional basilar membrane displacement evaluation criteria for evaluating the hearing compensation performance of the round window-stimulated middle-ear implant, and providing a theoretical basis for the performance evaluation of the round window-stimulated middle-ear implant. Methods an acoustic microscopic finite element model of cochlea was constructed based on experimental data of the geometry of cochlea. The reliability of this model was verified by comparing with experimental measurement values that include inner hair cells displacement, outer hair cells displacement, tectorial membrane displacement, etc. Based on this model, we comparatively analyzed the displacement of basilar membrane and the stereocilia shear displacement of the inner hair cells under forward stimulation and round-window stimulation. Using stereocilia shear displacement of the inner hair cells as the criterion of sense of sound, we studied the equivalent SPL deviation under round-window stimulation when using basilar membrane displacement under forward stimulation as the criterion of sense of sound. Conclusions At 5 kHz characteristic frequency of the studied slice of cochlea, under the sound pressures which have the same amplitude, the displacement of basilar membrane and the stereocilia shear displacement of the inner hair cells under round-window stimulation are lower than that under forward stimulation. Hence, under forward stimulation, the inner hair cells are more excited and the performance of sense of sound is better than that under round-window stimulation. Moreover, using displacement of basilar membrane as the criterion of hearing compensation performance of forward stimulation middle ear implant under round-window stimulation will overestimate hearing compensation performance of middle ear implant that uses round-window stimulation; but the deviation is relatively small; thus, it is a relatively reliable evaluation method.