An aminated epoxy cardanol glycidyl ether (NH.sub.2NC514) compatilizer, a preparation method and an application are provided, and the NH.sub.2NC514 is prepared by self-polymerization reaction of NC514 and grafting reaction with hydrolyzed KH550. When NH.sub.2NC514 is mixed with polylactic acid and bamboo fibers as a compatibilizer, a bio-based degradable bamboo-plastic composite material with excellent processing fluidity and mechanical properties can be obtained. The composite material is used for preparing the 3D printed product.