A semiconductor structure and a formation method thereof are disclosed. The formation method includes: providing a base; forming a dielectric layer on the base; forming a conductive via running through the dielectric layer; forming a conductive plug in the conductive via; forming a protective layer on the dielectric layer, wherein the protective layer covers the conductive plug; forming an aligner trench in the protective layer and the dielectric layer, wherein the aligner trench is isolated from the conductive plug; after forming the aligner trench, removing the protective layer to expose a top portion of the conductive plug; and after removing the protective layer, forming a magnetic tunnel junction (MTJ) laminated structure on the conductive plug. The protective layer formed in embodiments and implementations of the present disclosure may play a role of protecting the conductive plug, so as to prevent formation of metal oxide caused by oxidization of the conductive plug, which is then conducive to enabling the MTJ laminated structure and the conductive plug, correspondingly improving contact performance of the MTJ laminated structure and the conductive plug, and further improving performance of a magnetic random access memory (MRAM) device.