A new method to prepare polycrystalline silicon thin film from a-Si thin films using aluminate solution as induced source was introduced in this article. According to the analysis using optical microscope and Raman spectrum, it was indicated that the a-Si thin film could successfully be crystallized in certain Al-salt solutions. Using the X-ray photoelectron spectroscopy explored by shelling the samples into several sub-layers, the possible chemical reaction between the surface of silicon and aluminate solution was found and the continuous layer exchange process was confirmed. In the end, the mechanism of solution-based aluminum-induced crystallization was discussed.