Abstract: In order to improve the quality of tough biscuits and select suitable modifiers, in the paper, the specific volume, texture and color of the biscuit, texture properties and solvent retention of biscuit powder were used as indicators, L-cysteine hydrochloride (CYS), neutral protease, papain, bromelain and xylanase were added to low-gluten flour to study the effects of CYS and enzymes on low-gluten flour and the quality improvement of tough biscuits, meanwhile, correlation analysis and principal component analysis were performed to study the correlation between the indicators and the comprehensive effects of different additives simultaneously. The results showed that 150 mg/kg was the optimal amount of protease, compared with the blank group, the protease could increase the specific volume of biscuits, the increase of specific volume was as high as 12.42%, meanwhile, the protease could reduce the hardness, chewiness and adhesiveness of biscuits, with a maximum reduction of 78.88%, 87.38%, and 60.37%, respectively. There was no significant difference in the color of biscuits, and its effect was better than CYS and xylanase. Correlation analysis showed that the specific volume, adhesiveness, chewiness and hardness of the biscuits were correlated with the gluten elasticity index of the biscuit powder positively. The correlation coefficients were 0.808, 0.810, 0.810 and 0.810, respectively, indicating that low-gluten powder with low water absorption, low gluten content and small viscoelasticity was more suitable for the production of tough biscuits. Principal component analysis showed that bromelain had the best effect on improving the quality of tough biscuits and could replace the chemical additive CYS effectively.