The optimal of soy protein-galactomannan conjugates with excellent emulsifying properties were studied with three factorial quadratic orthogonal rotation design.The effects of hydrolysis time of guar gum,the weight ratio of soy protein and polysaccharide,and the dry heating time of soy protein and polysaccharide mixture were discussed.The regression equations of emulsifying activity and emulsifying stability were established as Y1=0.757 1-0.047 56X1+0.048 13X2X3-0.1143 X21-0.060 35X22-0.026 21X23 and Y2=78.92+1.126X1-2.873X2-2.35X1X2-1.375X2X3-0.99X22 respectively.The optimal conditions to prepare this polymer emulsifier were:hydrolyze guar gum for 75 min,mix the soy protein and hydrolyzed guar gum with the weight ratio of 50∶50,and then dry heat this mixture at 60℃ for 144hr.The validation tests showed that the emulsifying activity and stability of this conjugates perfectly fit the theoretical values predicted by these two regression equations,and the results of this paper provide theoretical principles to prepare this new natural polymer emulsifier.