Abstract: In order to improve the quality of bread supplemented with 25% sweet- potato flour,bread improvers were commonly used,such as wheat gluten,emulsifieres,hydrocolloids,enzymes and VC.Effects of different kinds of bread improvers on rheofermentation properties as well as farinogram properties were studied.Results showed that in single factor experiment,the addition of gluten had certainly improved dough fermentation characteristics,and the additions of 4.5% and 5.5% had the most obvious improvement. For other modifiers,emulsifier- diacetyl tartaric acid ester of monoglycerides( DATEM),sodium stearoyl lactic acid( SSL),hydroxypropyl cellulose( HPC),carrageenan,enzymes- glucose oxidase( GOX),xylanase( XYL),lipase( LYP) and ascorbic acid( VC) had different effects on dough fermentation,but hydroxypropyl cellulose( HPC) and lipase( LYP) had no effect on farinogram properties. Using ratio test and response surface design,treating bread hardness and specific volume as indicators,this experiment determined the formula of the compound modifier: compound emulsifieres 0.47%,carrageenan 0.58%,compound enzymes 0.0221%,VC0.00225%,which the theory of specific volume and hardness were 5.01 cm3/ g and 166.3 g,respectively.To test the accuracy of the model,the validation experiment was done under the optimum condition. Bread specific volume was 5.08 cm3/ g and hardness was 171.5 g,which both significantly higher than the control group of specific volume 4.02 cm3/ g and hardness 271.1 g.