Lead-cooled fast reactor is a promising reactor type of the fourth-generation reactors. In the design of the cladding material, it is necessary to pay attention to the compatibility of the cladding material with the molten Pb-Bi alloy, and its resistance to liquid metal corrosion, especially, the properties of structural materials will be significantly degraded by the synergistic action of corrosive molten Pb-Bi alloy and external stress. The Small Punch Test (SPT) is a testing method, that uses a small size sample to assess the changes in the mechanical properties of a structural material in service conditions. This method can extract samples directly from the structural material in use without compromising its integrity. Therefore, the SPT is very suitable for situations where the number of materials under study is limited or where materials in service are studied. This paper briefly introduces the SPT technique, summarizes the research on the correlation between the SPT and the standard size test at home and abroad, expounds the research on mechanical properties of key materials by using small punch technique, especially expounds the application of SPT in the study of liquid metal embrittlement effect (LME) of structural materials. The results can provide technical methods and theoretical support for the application of small punch technique in the study of liquid Pb-Bi alloy induced embrittlement of engineering materials.