A novel polyester P(DHCA-co-LA) based on 3，4-dihydroxycinnamic acid (DHCA) and D，L-Lactic acid (LA) was synthesized by the thermal polycondensation method.The structures and molecular weight of P(DHCA-co-LA) copolymers were characterized by Flourier transform infrared spectroscopy (FTIR)，nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC). Obvious changes of molecular weight and molecular weight distribution could not be observed when the ratio of DHCA to LA was varied.The thermal and optical properties of the copolymers were investigated by differential scanning calorimetry (DSC)，UV spectroscopy and fluorescence spectroscopy.It was found that the P(DHCA-co-LA) copolymers showed evident glass transition temperature (Tg).Tg of the copolymers decreased from 132.3℃ to 99.1℃ as the LA content increased from 0 to 50 mol%.The fluorescence spectroscopy indicated that P(DHCA-co-LA) copolymers had the strongest fluorescence emission at LA content of 20 mol%.The copolymer solutions exhibited a maximum absorption at 302 nm due to cinnamoyl groups

and the absorption decreased with increasing the UV-irradiation time，indicating that the cinnamoyl group could undergo a photochemical reaction.But the rate of cross-linking reaction is low，which would be responsible for the branched polymer chains.The cross-linked particles with diameter of about 20 μm still have good fluorescence after 65 min UV-irradiation.The X-ray diffraction (XRD) results showed that P(DHCA-co-LA) copolymers were amorphous and these copolymers may have good biodegradable performance.Copolymer rectangular samples，which were buried in soil for 5 months degradation experiments showed that the more LA contents in copolymer，the slower degradation rate of the copolymer，so the speed of copolymer degradation could be controlled.