A series of thermoplastic elastomer copolymers were prepared by melt polymerization using dimethyl terephthalate(DMT)/1,4-butanediol(BD)/poly(tetramethylene ether) glycol(PTMG) and DMT/BD/poly(3-methyl pentamethylene adipate) glycol(PMPA). The effects of chemical structure on the properties of thermoplastic elastomer copolymers were examined by incorporating two different polyol units in the polymer chain. Copolymers that were melt processible at low temperature below 20$0^{circ}C$ were obtained with inherent viscosities in the range of 0.5~0.9. The glass transition and melting temperatures, hardness and apparent crystal size of the copolymers were increased with increasing hard segment content. The copolymers based on PMPA have higher glass transition temperature and maintain stiffness to higher temperature than those of the copolymers based on PTMG at the same hard segment content. However, the melting temperature and apparent crystal size of the copolymer based on PTMG were higher than those of the copolymers based on PMPA. The Shore A hardness of copolymers, depending on the hard segment content, were in the range of 16~96.