The present invention relates to a preparation method for patternization of metal electrodes in silicon solar cells. After disposing an amorphous silicon layer on a silicon substrate processed by diffusion, laser light is projected on the amorphous silicon layer for patternization, and transforming the amorphous silicon with low optical conductivity into polysilicon with high optical conductivity thanks to the recrystallization process of the laser light. Then, after immersing the amorphous silicon layer in plating liquid, metal electrode can be formed accurately at the spots of the amorphous silicon layer patterned by laser light. No external voltage is required; plating reaction is induced by illumination directly.