Abstract: The Mn-Si powder porous alloys were prepared by solid phase sintering, using high purity Si powders and Mn powders as the raw materials. The microstructure and properties of Mn-Si powder porous alloys were characterized and the for mation mechanism of pores in sintering process was analyzed. The results show that, the MnSi powders can be obtained at 600℃, with the increase of sintering temperature to 1000℃, the original diffraction peaks of Si and MnSi disappear, only Mn₅Si₃ phase is present inthe sintered body. The expansion ratio and porosity of the sintered body first increase and then decrease with the increase of sintering temperature, and show the maximum values (8.86% and 54.26%) at 800.℃ There is an obvious gap between Mn particles and MnSiphase, as the diffusion between Si and Mn continues, the gaps increase and then connect to form the lamellar structure; as the sintering temperature rises to 1000, Mn, Si, ℃ and MnSi is used up, the Mn₅Si₃ structure is formed.