Abstract: Maleic anhydride (MA) and glycidyl methacrylate (GMA) were grafted onto poly(butylene succinate-co-butylene adipate) (PBSA) molecular chains in the melt state by using dicumyl peroxide (DCP) as an initiator. Compatibilizer marked PBSA-g-MG was successfully prepared. The chemical structure of the compatibilizer was characterized by FT-IR and ¹H-NMR. The effect of PBSA-g-MG dosage on mechanical properties, microstructure, dynamic mechanical properties and water absorption of fiber-reinforced thermoplastic starch (TPS)/PBSA composites were also studied. The results showed that PBSA-g-MG improved the interface compatibility of TPS/PBSA composite, and made T_g of TPS phase and that of PBSA phase close to each other. The mechanical strength and water resistance of TPS/PBSA also improved due to the introduction of PBSA-g-MG. The mechanical strength of TPS/PBSA composite with 8% mass fraction compatibilizer reached 19.4 MPa at 59% relative humidity, which was nearly 130% higher than that of non-compatibilized composites.