Objective to study the active acid on rhubarb '-azo(isobutyl processes two AAPH) trigger HCL)(red blood cell hemolysis inhibition of man,which produces reaction kinetics extra inhibit period and the concentration in red blood cells rhubarb acid concerned.Methods using ultraviolet spectrophotometry research rhubarb acid and AAPH the reaction in the aqueous phase.Results AAPH can be directly and rhubarb acid reactive,capturing the water phase on free radicals,red blood cell hemolysis.Conclusion rhubarb acid as an antioxidant,can effectively protect red blood cells.