To improve the yield and purity of 2，6-dimethyl-4-hydroxyphenylpentazole， the preparation method of 2，6-dimethyl-4-hydroxyphenylpentazole （DMAPH） crystal， the raw material of arylpentazole， was investigated through three steps including nitrification， reduction and salification from 2，6-dimethylphenol （DMP）. The structure， crystal morphology and stability were characterized with infrared spectroscopy （IR）， single crystal X-ray diffraction （SCXRD）， scanning electron microscopy （SEM）， powder X-ray diffraction （PXRD）， differential scanning calorimetry （DSC） and theoretical calculation. The results reveal that the yield of 2，6-dimethyl-4-nitrosophenol is up to 90% in the presence of glacial acetic acid and sodium nitrite. The different shapes of DMAPH crystal including sheet， needle， block and plate morphology can be obtained by changing the solvent， while the temperature only affect the particle size of precipitated crystals. The （400） face is the main crystal face of DMAPH crystal from methanol， while in other solvents it is the （214） face. The DMAPH crystals exhibit good thermal stability with decomposition peak temperature ranging from 220-240 ℃. In contrast to amorphous DMAPH powders， the crystalline DMAPH solids have better stability in air， and are more suitable for long-term storage.