A novel multiblock poly(ester urethane) (PBESTU) was synthesized through chain-extension reaction of hydroxyl-terminated poly(butylene succinate) (PBS-OH) and poly(ethylene succinate-co-ethylene terephthalate) (PETS OH), using toluene-2,4-diisocyanate (TDI) as chain extender. The chemical structure and molecular weight of PBESTUs were characterized by H-1 NMR, intrinsic viscosity, and GPC. The thermal behaviors were investigated by DSC and TGA. The resulting copolymers, PBESTUs, have a sole glass transition temperature (T-g), which indicated that the two segments, PETS and PBS, were well compatible in the amorphous phase. PETS segment enhanced the thermal degradation temperature of PBESTUs. The DSC and WAXD results showed that PBS segment made great contribution to the crystallization of PBESTUs. PBESTUs possessed excellent mechanical properties according to tensile testing.