Optical nanosurface whose RMS of roughness is at the nanoscale, is widely used in microelectronics and optical instruments. Optical nanosurface processing defects mainly contain surface damage and subsurface damage. Because of the advantage of non-destructive testing, we analyze the measurement technique of surface scattering theory and white light interferometry. Then the test samples with different processing defects are prepared from different technological conditions, and are measured by three different techniques, such as white light interferometer, atomic force microscopy and surface scattering measuring instrument. Comparison of experimental results show that white light interferometry is an effective measurement means for the measurement of surface roughness and subsurface damage with high precision, high speed and no other damage during the testing.