Intrinsic amorphous silicon thin films were prepared by plasma enhanced chemical vapor deposition method，and the crystallization of the films by 488 nm and 514 nm continuouswave laser under different power densities and irradiation time were studied by microRaman spectroscopic measurements. It is shown that intrinsic amorphous silicon films are able to be crystallized within 60 s at laser power densities is above 1.575×105 W/cm2. When the power density reaches to 2.756×105 W/cm2, there is transformation from amorphous silicon to singlecrystalline silicon. With the increase of the laser power density, it is still singlecrystalline silicon. At the laser power density of 2.362 ×105 W/cm, 60 s irradiation time crystallized the effect is better; and at the power density of 2.756×105 W/cm2, the effect of crystallization with 488 nm wavelength is better than that of with 514 nm in 60 s, and they are all singlecrystalline silicon.