The invention discloses a method for reducing resistance of a source and a drain. By the method, the resistance of a source region and a drain region can be reduced. The method comprises the following steps of forming a grid region, the source region, the drain region and a side wall on a substrate; forming a semiconductor layer on the source region and the drain region; depositing a mask layer, and selectively receiving a part of the mask layer; etching the semiconductor layer; and removing the mask layer, and thereby forming a bulge structure on the source region and the drain region.