Abstract: A reaction rod retainer for vacuum booster and a method for retaining a reaction rod, the reaction rod retainer for vacuum booster comprising a hollow annular body, wherein a plurality of outer ribs extend radially outwardly from an outer edge of the body, and wherein a plurality of inner ribs extend radially inwardly from an inner edge of said body. The reaction rod retainer guarantees tightness and firmness of combination of the reaction rod and feedback plate, in addition, it has an advantage of simple structure and meanwhile reduces the cost. The method for retaining reaction rod provided also has advantages of simple assembly and being easy to assemble.