Abstract: This paper introduces an on-the-fly Doppler broadening method considering the effect of thermal motion based on the stochastic sampling algorithm, at every collision sets. The method only requires the cross sections at a temperature of 0K, but not the the temperature distribution in the model material, and consequently to eliminate the need of Doppler processing codes. At first, this paper implements the Doppler module to validate the SDB method on the microscopic level, then combining the Reactor Monte Carlo code（RMC）, implements its on-the-fly Doppler broadening function to validate the SDB method on the macroscopic level. On the basis of current study, the capability of the SDB method to deal with temperature reactivity effect is proved.