Comparison effect of microwave power, irradiation time and mass quantity on activation desulfurization of molybdenite and conventional oxidative roasting was experimentally studied; unreacted shrinkage nucleus model of gas-solid heterogeneous reaction was adopted to study reaction kinetics. Results showed that molybdenite concentrate had good microwave absorption performance, and optimum desulfurization effect was obtained with 0.64kW microwave irradiation on 30g molybdenite for 6 minutes, the relative sulfur content rate was reduced 65.47% by contrast with traditional oxidizing roasting; the oxidation of molybdenite is highly exothermic with faster oxidation rate at higher reaction temperature; the conversion rate is obviously increased at 540~630 °C with interfacial chemical reaction as rate controlling step. The effect of microwave activation of molybdenite concentrate prior to conventional oxidative roasting has been tested and verified. As for industrial application, a short-time activated calcination pretreatment can be used to assist conventional oxidative roasting, and an optimized process with fast reaction rate and a low sulfur content of molybdenum calcine can be obtained.