Hydrogenated microcrystalline silicon (μc-Si:H) materials was prepared by plasm a enhanced chemical vapor deposition (PECVD) at silane concentration 6% and 7% w ith changing excitation frequency (40—70MHz). Relationship between excitation f requency and electrical, structural characteristics and deposition rate of the m aterials was studied. The results indicate that the crystalline volume fraction (Xc) decrease firstly and then increase with the increase of excitati on frequency. But the photosensitivity and the deposition rate be have adversely with the change of excitation frequency. The reason of change of structure and deposition rate of thin films with excitation frequency was studied by optical e mission spectroscopy.