Recycled Poly (ethylene terephthalate) (PET) was blended with Polycarbonate (PC) together with elastomers. Three kinds of elastomer: POE (ethylene-octene copolymer), SEBS(styrene-ethylene/butylenes-styrene triblock copolymer) and SEBS-g-MA (maleic anhydride grafted SEBS) were selected. Scanning electron microscope (SEM) results showed the alloy blended with SEBS exhibiting smallest particle size distribution and it had better mechanical properties than the others, especially in broken-elongation and impact strength. The alloy blended with SEBS-MA didn't reach high performance was due to the existence of small amount of active monomer: MDI (methylenediphenyl diisocyanate). The preferential reaction by SEBS-MA with MDI not only resisted the chain-extending progress induced by MDI but also resulted in coalescence of SEBS-MA. In addition, though SEBS was the best selection to this system, experimental results showed that the weight ratio of SEBS must also be limited in a certain degree. Over much contents of SEBS resulted in coalescence together affect compatibility between components.