Aluminum-induced crystallization of amorphouse silicon (a-Si) is a suitable method for preparation of polycrystalline silicon (poly-Si) films. Biasing an electric field, which is perpendicular to the surface of the a-Si films, will accelerate the mutual diffusion of Al atoms and Si atoms in the interface during the aluminum-induced crystallization process and enhance the crystallization of the a-Si films obviously. The experimental results show that under the action of the electric field, more than 60% of a-Si transfer into poly-Si when the a-Si film was annealed at Ta＝400℃ and annealing time ta=60min; the a-Si films have obviously crystallized at Ta＝450℃ and ta=30min; at Ta＝500℃ and ta=15min, the XRD intensity of crystalline silicon (c-Si) components in the films is thrice to fourfold as strong as that in the films without the effect of an electric field.