A series of polybutylene terephthalate (PBT)- b- polytetrahydrofuran (PTMG) polyether ester block copolymers (TPEE) with different soft and hard segment contents were synthesized by direct esterification melt polycondensation. The effects of different soft and hard segment mass ratios and soft segment molecular weight on the structure, molecular weight, thermal properties and viscoelasticity of the materials were investigated by FT-IR, ¹H-NMR, XRD, DSC and DMA. The results show that the characteristic viscosity of TPEE is higher than that of PBT at the same discharge power, and decreases with the increase of the mass fraction of hard section or molecular weight of soft section; the decrease of its melting point increases with the increase of the molar fraction of soft section; the micro- phase separation structure exists in TPEE, when the mass fraction of hard section is 60%, and the number-average molecular weight of soft section is 2×10³, and the loss angle tangent peaks representing the glass transition of PBT in hard segment and PTMG in soft segment respectively appear. The results of the study provide some reference for the synthesis and application of TPEE.