Reduced-fat sausages were prepared by replacing pork back fat with barley flours of different particle sizes. Three barley flour fractions with different particle size were obtained by passing the ground barley material through a sieve. Fraction 1 and 2 had a higher water absorption index than other fraction and showed higher peak and final viscosities due to higher ${eta}$-glucan content. Therefore, fraction 1 and 2 were used as a fat replacer in preparation of reduced-fat sausages. Response surface methodology was employed to optimize the formulation of reduced-fat sausage and the effects of fat content and barley flour paste concentration on the textural properties were analyzed simultaneously. Using a regression model, the optimum formulation of reduced-fat sausage was calculated. For fraction 1, calculated levels of fat content and paste concentration were 7.6 and 3.9%, and for fraction 2, levels were 6.7 and 6.9%, respectively.