Ammonium nitrate is a promising rocket propellant oxidizer. It is present as the major component in most industrial explosives. Due to the surface polarity of ammonium nitrate, the particles can easy absorb moisture. In this study, ammonium nitrate particles were coated by cetylalcohol surfactant in order to reduce the hygroscopicity. The optimized physical coating process using cetylalcohol was achieved by (L9 (34 )) Taguchi orthogonal array (TOA).The analysis of TOA revealed that the highest decline of absorption rate was 35.45% with the mass ratio of coating layer was 0.95%. Scanning electron microscopy (SEM) was used to characterize the surface of coated and uncoated ammonium nitrate. The idea and approach presented in this study can help the researchers to improving anti-hygroscopicity of ammonium nitrate.