A new type of biodegrad-able polyesteramide P(LA/AU) based on lactic acid and aminoun-decanoic acid was synthesized by the meh polycondensation method. The copolymers obtained were charac-terized by FTIR. 1H-NMR, DSC, and XRD. The in vitro degradation behavior of the copolymers was studied using weighing. 1H-NMR. FT1R, DSC. and SEM. With the increase in aminonndecanoic acid units, the mehing temperature and crystallinity increased, but the water absorption and degradation rate decreased accordingly. During degradation in vitro, the ester moiety decreased due to ester cleav-age along the macromolecular main chain. As degradation proceeded. the mehing temperature and crystallinity increased at first, then started to decrease because the crystalline phase was destroyed.