A new type of biodegradable polyesteramide P(LA/AU) based on lactic acid and aminoundecanoic acid was synthesized by the melt polycondensation method. The copolymers obtained were characterized by FTIR. 1H-NMR. DSC. and XRD。 The in vitro degradation behavior of the copolymers was strdied using weighing. H-NMR, FTIR. DSC, and SEM. With the increase in aminoundecanoic acid units, the milting temperature and units, the melting temperature and crystallinity increased, but the water absorption and degradation rate decreased accordingly. During degradation in vitro, the ester mority decreased due to ester cleavage along the macromolecular main chain. As degradation proceeded, the melting temperature and crystallinity increased at first, then started to decrease because the crystalline phase was destroyed.