In order to reveal the relationship between 3,3-bis(azidomethyl) oxetane-tetrahydrofuran copolyether (P(BAMO-THF)) microstructure and its macro properties, the segment sequence structure of a kind of P(BAMO-THF) was characterized using quantitative C-13-NMR analysis. It was found that the P(BAMO-THF) is composed of equimolar comonomers whose randomness factor (R) is 1.09, belonging to a quasi-ideal random copolymer. Combining DSC and polarizing optical microscopy, it was verified that the thermal-effect between 28 degrees C and 41 degrees C attributes to the melting of the P(BAMO-THF)spherulites. Using WAXRD, it was suggested that the aggregation of BAMO micro-blocks among P(BAMO-THF) polymeric chains causes the formation of spherulites. The viscosity measurement clearly demonstrated that, below 30 degrees C or above 40 degrees C, the P(BAMO-THF) viscosities change slowly as a function of temperature. Conversely, between 30 degrees C and 40 degrees C, its viscosities sharply decline with the increase in temperature because of the changes in its morphology.