Abstract: In order to improve the solubility of oat protein isolate(OPI),succinylation was used to modify the proteins. The effects of the temperature of reaction,p H,the ratio of succinic anhydride,and the concentration of proteins on solubility were studied by single factor experiments. The changes of structure of OPI were analyzed by fluorescence emission spectra. Through the response surface methodology,the optimal conditions were as follows:the temperature of reaction 50 ℃,p H8.5,the ratio of succinic anhydride 10% and the concentration of proteins 4 %. The solubility of OPI reaches to 68. 38 % in the optimal conditions. Fluorescence intensity of succinylated oat protein isolate increased,which was obtained by fluorescence emission spectra. The increasing of fluorescence intensity was due to more exposed leucine which were caused by the expanding of the structure of side chains.