3D printing is an additive manufacturing (AM) technology that has developed rapidly in the past decades due to its advantages, such as freedom of design, mass customization, waste minimization, and the ability to manufacture complex structures, as well as fast prototyping. Various materials are used in 3D printing, including metals, polymers, ceramics, concrete, and their composites. The polymer's easy processing makes it stands out among many materials. As a thermoplastic polymer, polylactic acid (PLA) received more attention as an effective biomedical material due to its proven biodegradation and biocompatibility. Herein, the development of 3D-printing technology is summarized and various applications of 3D-printed PLA and their composites in orthopedics are introduced. Furthermore, the current limitations and future opportunities in 3D printing are also discussed to help guide the 3D-printing development and improve 3D-printing strategies in orthopedic.