The invention discloses a method for removing residual defect after photoresist developing. The method comprises the following steps: step one, forming photoresist on a wafer and carrying out exposureand developing to form a photoresist graph, and carrying out pre-defining on the size of the photoresist graph by exposure; step two, carrying out photoresist pre-treatment process to completely remove photoresist residue existing in a developed region. Meanwhile, by the photoresist pretreatment process, the size of the photoresist graph is reduced, and through the pre-defined size and the reduced size, the final size of the photoresist graph reaches the target size. By the method, residue after photoresist developing can be removed, and thus, dielectric layer residue after follow-up dielectric layer etching is eliminated.