Abstract: Influence of different bias voltages on microstructures and residual stress of aluminum coatings is investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray stress analyzer, respectively. The result shows that the microstructures are influenced strongly by bias voltages, of which are worst at - 300 V and at low bias voltages are better than at 0 V. The preferential orientation of crystal planes shift from (111) to (200) above -200 V. The residual stress of all coatings is small, which has a change from tensile to compressive stress with the increase of bias voltages.