In order to increase gel strength of the final products,soy protein isolate was covalent modified by glucose.Based on single factor experiment,soy protein isolate covalent modification conditions were optimized in Box-Behnken model.The gel strength of the complexes under various conditions were identified and analyzed.The results showed that the optimum reaction conditions were: the augmenter of glucose was 1.0%,reaction temperature was 60℃,reaction time was 50min.The gel strength could reach to 1 865.02g which increased 20% compared with the unmodified soy protein isolate.Experiment proves that the modification technology was effective and significantly improved the gel strength of soy protein isolate.