It is known that the direct contact between Al and a-Si enhances the crystallization of a-Si film. But the poly-Si films crystallized by the direct contact of Al metal film suffer the problems of rough surface and pores. In our study, we utilized the vapor from AlCl3 instead of Al metal film. The crystallization was enhanced by annealing a-Si films with AlCl3 that the crystallization was completed in 5h at 540. And the surface was as smooth as that of the a-Si film. The Al incorporation into the poly-Si film took place, but the content was below the detection limit of AES.