Regenerated rigid polyurethane(RRPU) was prepared with tetraethylenepentamine (TEPA), TEPA/diethylene glycol (DEG) and triethanolamine (TEA) as the decrosslinking agents. Polyvinylchloride (PVC)/RRPU composites were prepared by melt blending. Effect of decrosslinking agents on the mechanical properties and micro morphologies of composites were analyzed by dynamic mechanical analysis meter, scanning electron microscope. The results show that the decrosslingking degree order of the three agents is TEPA>TEPA/DEG>TEA. PVC/RRPU composite decrosslinked with TEPA agent show the satisfying mechanical properties. With the addition of RRPU powder, the storage modulus （E′）and glass transition temperature （Tg） increase compared with those of pure PVC. A better phase interface adhesion could be seen in the impact fracture surface of PVC/RRPU composite treated with TEPA. The most obvious phenomena of fracture tearing could be observed in its tensile fracture surface. The composites exhibit better mechanical properties.