To investigate the effects of machining techniques and parameters on the ultra-precision machined surfaces,the power spectral density(PSD) method was employed to characterize the ultra-precision machined surfaces.Dimension 3100 AFM was used to measure the surfaces,and then the 3D micromorphology and corresponding data were obtained.The PSD graph was drawn with the spatial wavelength as horizontal axis and the power spectral density as vertical axis.The spatial wavelength distribution as well as the proportion on the machined surfaces was simply and directly analyzed.The relationship between power spectral density and machining methods as well as the machining parameters was comparatively analyzed.Experimental results show that by using the PSD method to characterize the ultra-precision machined surfaces,the lateral and height size features can be illustrated,and the distribution information of spatial wavelength of the machined surfaces can be obtained.Meanwhile,the anisotropic features of the machined surfaces can be also analyzed through the 3-D power spectral density graph.