Series of the hydroxyl-terminated co-polyethers whose molecular weight is around 2 000 were synthesized by controlling the rate of THF and ECH and the dosage of initintor. Varied types of modified UV curable waterborne polyurethane emulsions were synthesized by using the co-polyethers acting as soft segment, and the corresponding product structures were characterized by using FTIR. The results have shown that: with the increasing ratio of epoxy chloropropane, the strong polarity halogen atoms in the soft segment increases while the tensile strength of curable film changes from 4.6 MPa to 6.7 MPa and the elongation at break reduces from 162% to 113%. When the ratio of THF and ECH grows to be 1∶1, the weightlessness temperature of 5% and 10% increases from 164 ℃ to 200 ℃ and 220 ℃ to 275 ℃. In addition, the adhesion of the coating significantly increases to 1 level, also the hardness and impact resistance performance improves.