PC/ABS alloy was prepared through melt blending process by using PC,ABS and different kinds of compatibilizing agents. The structure and mechanical properties were characterized by DSC and normal mechanical measurement methods. The results show that PC/ABS belongs to partially-compatible system, the compatibility and mechanical properties could be improved when compatibilizing agents ABS-g-MAH and PE-g-MAH were added to the blending system. The modification effect of ABS-g-MAH is better than that of PE-g-MAH. The reason is that the similar molecular structure of ABS-g-MAH and PC/ABS alloy, at the same time, the interface adhesion could be improved through ester exchange reaction between acid anhydride in ABS-g-MAH and PC.