The work aims to prepare polylactic acid(PLA)/cassava starch (CS) and PLA/high amylose starch (HAS) biodegradable packaging materials to compare effects of compatibilizers on the compatibility, mechanical properties and crystallization properties of the composites and optimize the experimental formula of PLA/HAS composites. The HAS and CS modified PLA composites were prepared by melt blending method. The chemical structure, mechanical properties, microstructure and crystallization properties of the composites were characterized. Then, the response surface method was used to optimize the experimental formula of PLA/HAS composites. The results of Fourier transform infrared spectroscopy (FTIR) indicated that the epoxy groups on glycerol triglycidyl ether (GTE) reacted with the hydroxyl groups on PLA and starch to achieve reactive compatibilization. The mechanical results showed that the tensile strength and elongation at break increased first and then decreased with the increase of compatibilizer content, and reached the maximum values when the compatibilizer content was 4%. The results of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) indicated that the addition of compatibilizer improved the compatibility and crystallinity of the two-phase system. In terms of mechanical properties, crystallinity and compatibility, the performance of PLA/HAS composites was superior to that of PLA/CS composites. The optimized formula of PLA/HAS composites was as follows:HAS content was 18%, compatibilizer content was 4%, and the number of functional groups of the compatibilizer was 3. High epoxy value compatibilizers such as GTE, ethylene glycol diglycidyl ether (EGDE) and pentaerythritol glycidyl ether (PGE) can effectively improve the compatibility between PLA and starch, and PLA/HAS biodegradable packaging materials have good application prospects.