Abstract: Focusing on the problems of contamination and deformation failure of the sample holder in the ion beam thinner, molybdenum metal was used instead of ordinary stainless steel as the fixture material. The project was designed and verified in practice. The results showed that the use of molybdenum metal as the fixture material can significantly improve the life of the ion gun and its important components, reduce the pollution of the work chamber and cross-contamination between samples, and improve the quality of thinned samples and the trueness of the structure and element analysis. Therefore, the study has important application value.