The washing process and deacidification kinetics for RDX were investigated using the ultrasonic technique. The effects of ultrasonic time, temperature, ultrasonic frequency and ultrasonic power on the washing and deacidification for acidiferous RDX with acidity as the evaluation indicator by the single factor test were discussed. The conditions of ultrasound-assisted washing process were optimized by orthogonal experiment. The related dynamic model was deduced and the activation energy was obtained. Results reveal that, the influence order of four factors is ultrasonic time>ultrasonic frequency>temperature>ultrasonic power, the optimum parameters are ultrasonic time of 70 min, temperature of 35 ℃, ultrasonic frequency of 40 kHz, ultrasonic power of 85%.The deacidification process is in conformity with pseudo-first order kinetics, the activation energy is calculated as 7.105 kJ·mol^-1, and the results of model analysis are verified by the results of experiments. Ultrasonic treatment brought about no changes of the molecular structure and representative functional groups of RDX.