A semiconductor structure and a method for forming the same are provided. In one form, the method includes: providing a base, where a bottom core material layer is formed on the base, a plurality of discrete top core layers is formed on the bottom core material layer, an area between top core layers of the plurality of adjacent top core layers is a groove, and the groove includes a connecting groove; forming a first spacer film conformally covering the plurality of discrete top core layers and the bottom core material layer; forming a blocking structure in a remainder of the connecting groove exposed from the first spacer film; removing first spacer films on a top of the top core layers of the plurality of discrete top core layers and on the bottom core material layer using the blocking structure as a mask, to form a first mask spacer; removing the plurality of top core layers; patterning the bottom core material layer using the first mask spacer and the blocking structure as a mask, to form a bottom core layer; forming a second mask spacer on a side wall of the bottom core layer; and removing the bottom core layer. Through the blocking structure, a bottom core layer at a position corresponding to the connecting groove has a relatively large width, thereby directly forming target patterns with different spacings.