The present invention provides a method for crystallizing a metal oxide semiconductor layer, a semiconductor structure, a method for manufacturing a semiconductor structure, an active array substrate, and an indium gallium zinc oxide crystal. The crystallization method includes the following steps: forming an amorphous metal oxide semiconductor layer on a substrate; forming an oxide layer on the amorphous metal oxide semiconductor layer; forming an amorphous silicon layer on the oxide layer; and irradiating the amorphous silicon layer by using a laser, so as to heat the amorphous silicon layer, where the heated amorphous silicon layer heats the amorphous metal oxide semiconductor layer, so that the amorphous metal oxide semiconductor layer is converted into a crystallized metal oxide semiconductor layer.