Molecular beam epitaxy HgCdTe/InSb materials need to prevent uncontrolled diffusion of In elements in HgCdTe. We use CdTe buffer layer as barrier layer to control In diffusion. In order to study the diffusion of In in CdTe materials, the CdTe/InSb samples are obtained by molecular beam epitaxy. Considering that In element may pollute the material through environmental diffusion during annealing, we use the SiO2 is as passivation layer, and find evidence of in element polluting the surface through environmental diffusion through comparative tests, which provides a new idea for controlling in element diffusion.