Objective To study the type and water content of water of crystallization in berberine hydrochloride bulk drug and the influence of berberine hydrochloride tablet preparation technology on the water of crystallization of active pharmaceutical ingredient, and to provide basis for improving the quality control of berberine hydrochloride tablets. Methods Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) were used to study the water of crystallization in berberine hydrochloride, the production process of berberine hydrochloride tablets and the change of water of crystallization during the stability investigation were also investigated. Results Berberine hydrochloride is mainly dihydrate and contains a small amount of tetrahydrate and free water, during the production process and stability investigation of berberine hydrochloride tablets, there was basically unchanged in water of crystallization of active pharmaceutical ingredient. Conclusions Defined the water of crystallization in berberine hydrochloride active pharmaceutical ingredient and controlling the quality of berberine hydrochloride tablets in the production process are helpful to ensure the uniform, stable and controllable quality of its preparation.