The erosion process and kinetics of PbTe particles in a selenium melt were investigated. The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures (573, 583, and 593 K), but the limiting step is controlled by boundary layer diffusion at high temperatures (603 and 613 K). The Se- and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens, with Kirkendall voids generating in the product layer accelerating PbTe particle erosion. After the PbTe impurities in the selenium melt evolve into PbSe and Te, Te is evenly distributed in the selenium melt owing to the solubility of Se and Te. This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.