Abstract: The relations of the morphology and property of several series of segmented PUU were studied in film form by using SME, DSC and tensile stress-strain data. The polyether-based and polyester-based PUU block copolymers were synthesized by using PPO-EO polyether or PBA polyester with different molecular weights, MDI and DETDA. Especially, the polyether-ester-based PUU were synthesized. The extent of phase separation inscreases with increasing molecular weight of soft segment. The polyether-based PUU shows the better phase separation than polyester-based with the same molecular weight of soft segment. The polyether-ester-based PUU shows the morphology of both polyether-based and polyesterbased PUU and with larger domain size and interface.