This invention relates to a method for forming SiNi2 layers and PMOS transistors, which first of all provides an n-type substrate of a grid structure to inject amorphous germanium onto the substrate , forms a source and a drain in the substrate of the two sides of the grid structure and anneals them, deposits a cover layer on the substrate and the grid structure and forms a Ni layer on the cover layer to be annealed, and the Ni layer is reacted with Si on the surface of the source and the drain to form a SiNi2 layer, eliminates unreacted Ni and cover layers to form a PMOS transistor after succeeded internal linking, in which, amorphous germanium is injected into n-type substrate before forming the source and the drain to turn monocrystal silicon in it to polysilicon then to be doped with germanium, therefore, Si2Ni4 will not be generated at the same time when the succeeded Ni layer reacts with the silicon substrate to form a SiNi2 layer nor peak phenomenon in the Si substrate.