the present invention relates to a method for exposing twice by two masks in a semiconductor process , which includes : providing a substrate having a surface ; forming a negative - type photosensitive material on the surface of the substrate ; providing a first mask having a first pattern ; performing a first exposure procedure on the negative - type photosensitive material by utilizing a first light beam through the first mask ; providing a second mask having a second pattern , wherein the entire texture of the second pattern is substantially identical to that of the first pattern ; and performing a second exposure procedure on the negative - type photosensitive material by utilizing a second light beam through the second mask . thus , the negative - type photosensitive material will not be damaged and will not cause yield loss .