To improve the low temperature elastic recovery and tensile properties of the traditional poly(ether ester), a series of randomly branched poly(ether ester)s consisting of poly(butylene isophthalate) as hard segment, poly(tetramethylene glycol) and poly(ethylene glycol) as mixed soft segment, and trimeth ylolpropane as trifunctional monomer were synthesized. The structure and composition of the samples were characterized by 1 H NMR and FTIR spectroscopy. The tensile strength, elongation at break and the low temperature elastic recovery were used to characterize the mechanical properties of the synthetic polymers.The results indicate that the branched poly(ether ester) showed an increment of mechanical and thermal properties with the increasing content of branching agent in the polymer matrix. Moreover, the low temper ature elastic recovery and tensile properties of branched poly(ether ester) were superior comparing to the tra ditional poly(ether ester)s.