In order to improve the toughness of PLA, bio-based nylon 11 was added to the PLA matrix material, and Joncryl 4468 was used as the compatibilizer, the PLA/nylon 11/4468 composites were prepared by twin screw melt blending. The influence of the content of the compatibilizer Joncryl 4468 on the crystallization, rheology and mechanical properties of the composite material was studied. The research results showed that the tensile strength and impact strength of the PLA/nylon 11/4468 composite material were significantly enhanced. When the mass fraction of PLA was 78.4%, the mass fraction of nylon 11 was 20.0%, and the mass fraction of compatibilizer Joncryl 4468 was 1.6%, compared with pure PLA, the tensile strength and impact strength of composite material were increased by about 10.4% and 40%, respectively, showing good comprehensive mechanical properties. The crystallinity of PLA in the PLA/nylon 11/4468 blend system was 3.5% higher than pure PLA. The addition of the compatibilizer Joncryl 4468 improved the processing properties of the composites.