SummarySuperfine and regular grinding methods were used to mill mulberry leaves (ML), and the chemical composition and physical characteristics of the powders were investigated. Compared to regular grinding, superfine grinding reduced particle size from 121.44 μm to 18.69 μm. Compared to coarse mulberry leaf (CML), the fine mulberry leaf (FML) powder had a greater water solubility index, soluble dietary fibre content and 1‐deoxynojirimycin (DNJ) content. Both types of ML powders were substituted for flour at various percentages (3%, 6%, 9% and 12%), and their effects on the biscuits' textural qualities and sensory assessment were examined. The adhesiveness, cohesiveness and springiness of biscuit doughs were all reduced by ML powder addition, while their hardness was raised. The inclusion of ML powders increased the hardness of the biscuits significantly, whereas only the addition of FML powders decreased their fracturability. Additionally, the DNJ contents in FML biscuits were significantly higher than that in CML biscuits. The sensory assessment revealed that biscuits containing 9% FML powder received the best rating.