A new dynamic calibration method as prediction-calibration-approximation used for calibration of propellants and explosives gas test by automatic gas combination system and calibration device was reported in this paper. The results indicate that the accurate measurement of multicomponent gas was achieved by dynamic calibration technology of multicomponent propellants and explosives gas. The relative standard deviation of Dynamic Calibration is less than 0.3%. As a result, the dynamic calibration technology ensures validity and unity of measuring value transfer in gas detecting.