Abstract: In order to utilize efficiently broccoli wastes, a comparative investigation of the effectiveness of six extraction methods (heating, acid extraction, alkaline extraction, heating in an acidic environment, heating in an alkalinic environment, acid-flocculation) for discarded broccoli leaf protein was studied. The results showed that acid flocculation was the optimal extraction condition. Three single factor such as material water ratio, pH value, chitosan concentration in acid flocculation extraction experiment were designed. Through orthogonal test, results implicated that these optimal conditions were as follow:ratio of material to water 1∶4 (g/mL) , pH4.0, chitosan concentration 0.4g/L. Under this condition, the content of discarded broccoli leaf protein concentrates was 14.79%, the extraction rate was 39.01%. The study determined the optimal extraction technology of leaf protein from discarded broccoli stems and leaves, which could provide the scientific basis for deeply exploiting and utilizing broccoli wastes.