3，4-Dinitropyrazole （DNP） has a moderate melting point， high density， and excellent detonation performance， and is regarded as a promising carrier explosive for melt-cast formulations. However， DNP exhibits a certain degree of hygroscopicity under high-temperature and high-humidity conditions， which may adversely affect charge-processing operations and the final performance of explosive products. The hygroscopic behavior of DNP powder was investigated using the desiccator equilibrium method. The effects of post-treatment method， temperature， relative humidity， and particle size on moisture sorption were evaluated. The influence of moisture uptake on the thermal decomposition behavior of DNP was further examined， and quantum chemical calculations were performed to predict its key moisture-sorption sites. The results showed that the post-treatment method had the most significant effect on the hygroscopicity of DNP， with benzene-recrystallized DNP exhibiting the lowest moisture sorption. Temperature and relative humidity had secondary effects， and the hygroscopicity of DNP increased with increasing temperature and relative humidity， whereas particle size had only a minor influence. When the ambient temperature was below 30 ℃， the critical relative humidity of DNP was higher than 84%， whereas it decreased to 75% at 40 ℃. Under the corresponding critical relative humidity conditions， the equilibrium moisture content of benzene-recrystallized DNP remained below 0.31%， with no obvious agglomeration or caking. Moreover， no significant changes were observed in the melting point or thermal decomposition temperature of DNP after moisture sorption. These results indicate that the hygroscopicity of DNP powder can be reduced through appropriate post-treatment and that moisture-related problems can be effectively prevented by controlling the environmental temperature and relative humidity. Quantum chemical calculations further identified the H atom of the –NH group on the pyrazole ring as the key moisture-sorption site of DNP.