The polybutylene succinate (PBS) was hydrophobically modified by various content of L-glutamic acid (Glu) and blended with phosphate starch (PPS) by emulsion-casting method to prepare PBS -co-Glu/PPS composite. The chemical structure of PBS-co-Glu copolyester was characterized by FTIR and 1H-NMR. The hydrophilicity, crystallinity and mechanical properties of PBS-co-Glu copolyester were analyzed by GPC, XRD, POM, SEM and tensile test, Lipase degradation experiment was performed to evaluate the degradability of composite materials. The results showed that the elongation at break of PBS-co-Glu/PPS composite increased with the increase of Glu content, and the value elongation at break reached the maximum when the Glu content was 4%, at the same time, transmittance and degradability were significantly increased.