RDX molding powder is prepared by water slurry. The effect of technical process on the coating RDX with polymer solution is studied. The effect of each factor was studied by the sensitivity and particle size. The desensitizing agent and polymer were added as mixture, vacuum pump was used to drive remain solvent in the process and sound result was obtained. Material adding rate,temperature,agitating rate,the secondary addition of ethyl acetate were the main factors affecting the preparation quality and sensitivity of the molding powder. Optimized parameters are obtained: reaction temperature 63 ℃ , agitating rate 300 r·min^-1, adding rate 0.06 mL·s^-1, the weight ratio of ethyl acetate added in the second time and polymer 4∶1. The order of factors affecting preparation quality and sensitivity of molding powder is as follows: secondary addition of ethyl acetate, agitating rate, temperature, material adding rate. Furthermore, secondary addition of ethyl acetate is the most important factor to affect the packing quality and particle size of the product.