Solid phase decarburization of high carbon ferrochrome powders (HCFP) mixed with calcium carbonate powders (CCP) can be realized at a certain temperature in microwave heating field. The modified kinetic model is used and the results illustrate that, gas inner diffusion is the restrictive step of decarburization reaction, and apparent activation energy of the reaction is 72.80 kJ mol−1, which is much lower than that of carbon gasification reaction by conventional heating. Backscattered electron image analysis shows that the carbides in decarburized ferrochrome powders vary with temperature. With the temperature rising, the ratio of (Cr,Fe)7C3 decreases, (Cr,Fe)23C6 and chromium ferrite increases in the microwave field. Meanwhile, the thickness of oxide film around the decarburized ferrochrome powders enhances, which hinders gas inner diffusion. The optimum conditions of solid phase decarburization of HCFP by microwave heating are 1100°C and holding for 60 min.