Abstract: Several Series of Copolyether- thermoplastic polyurethanes and polyurethaneur eas beded on different relative molecular mass ethylene oxide-tetrahydrofuran copolyether, 4, 4' -diphenyle methane diisocysnate/isophorone diisocyanate, 1, 4-butanediol /ethylene diamine were prepared . The struan and properties of these elastomers were characterized with Differential Scanning Carlorimetry, X-ray Diffraction, 13C Nuclear Magnetic Resonance techniques. The relationship between phase separation and soft phase T. was obtained, XRD results indicate that all IPDI-TPU and IPDI-TPUU are in completely amorphorous states.