The invention relates to a method for passivating a photoresist surface. The method comprises the following steps of: providing a semiconductor substrate; forming a patterned photoresist layer on the surface of the semiconductor substrate; and carrying out plasma treatment on the patterned photoresist layer surface to passivate the surface, wherein gas passing through the photoresist layer surface contains nitrogen and hydrogen. The invention has the advantages that plasma consisting of the nitrogen and the hydrogen is adopted to passivate the photoresist, and a dense passivation layer is formed on the surface of the photoresist layer, thus the influences of subsequent etching processes on the photoresist layer can be blocked so as to prolong the etching resistant time of the surface and guarantee the quality of graphic transition.