Abstract: The surface roughness of Zirconium oxide (ZrO2) thin films with different thickness and substrate roughness, which were deposited with different ion beam auxiliary energy by electron beam evaporation technique，was studied with Taylor Honson coherence correlation interferometer (Talysurf CCI). The influence of surface roughness of substrates, thickness of ZrO2 thin films and ion energy of ion beam assisted deposition (IBAD) on surface roughness of ZrO2 thin films was investigated. The results show that the surface roughness of ZrO2 thin films increases slowly with the increase of substrate roughness when the substrate roughness is less than 10nm, then increases quickly when the roughness is more than 10nm; the surface roughness of ZrO2 thin films decreases and then increases with the increase of both thickness and ion energy.