The epitaxial CdTe buffer layer between silicon and HgCdTe can reduce dislocation density of up to 107 cm-2 generated during epitaxial process. High-temperature thermal annealing is one of the effective methods to suppress dislocations in materials. The traditional out of place annealing technology will lead to process instability and impurity pollution, and in-situ annealing can effectively solve these problems. Dislocation suppress of Si-based CdTe grown by molecular beam epitaxy (MBE) was studied using in-situ annealing technique. The CdTe material with a thickness of about 9 m was subjected to six cycles of thermal cycling annealing at different temperatures. The effect of different annealing temperatures on the dislocation suppression of Si-based CdTe material was explained. Statistical dislocation etch-pits density method was used to compare the dislocation changes of materials before and after annealing. It can be found that the dislocation density can reach 1.2×106 cm-2 when the annealing temperature is 520℃, which is 0.5 orders of magnitude lower than that of the CdTe material without annealing.