Abstract: Extensograph was used to study the effects of different gluten reducing agent (protease and sodium metabisulfite) on the semi-sweet hard dough rheological properties. The result indicated that the dough rheological properties were well reflected by the extensograph index. Energy, maximum resistance and maximum ratio were linearly or negative powerly correlated with increasing protease and sodium metabisulfite levels, and positive (r>0.8) (p<0.0001) correlation coefficients were observed between extensograph index and the physical properties. Additionally, the effect on dough rheological properties of 1% water addition variation was well detected by the modified extensograph index. Two-way ANOVA analysis showed that there was significant (p<0.05) interaction effect on the extensograph index and biscuit physical properties between 1% water addition variation and gluten reducing agents.