Enzymatic ring-opening copolymerization of trimethylene carbonate (TMC) and ethylene ethyl phosphate (EEP) are performed in bulk at 100℃ using porcine pancreas lipase (PPL) or candida rugosa lipase (CL) as catalyst. The factors affecting the yield and molecular weights such as catalyst concentration, polymerization time and monomer feed ratio are investigated. The ran-dom copolymers obtained have molecular weight ranging from 3200 to 10200. The glass transition temperature (Tg) of the copolymers decreases from -28 to -41.7℃, with the increase of the EEP content in the feed from zero to 5∶10. Degradation tests show that the degradability of the co-polymers is improved by introduction of the EEP unit into the copolymer chain. Enzymatic ring-opening copolymerization of trimethylene carbonate (TMC) and ethylene ethyl phosphate (EEP) are performed in bulk at 100 ° C using porcine pancreas lipase (PPL) or candida rugosa lipase (CL) as catalyst. The factors affecting the yield and molecular weights such as catalyst concentration, polymerization time and monomer feed ratio are investigated. The ran-dom copolymer obtained has molecular weight ranging from 3200 to 10200. The glass transition temperature (Tg) of the copolymers decreases from -28 to -41.7 ° C with the increase of the EEP content in the feed from zero to 5:10. Degradation tests show that the degradability of the co-polymers is improved by introduction of the EEP unit into the copolymer chain.