Abstract: 3D printing construction technology is a new type of digital construction technology that applies 3D printing technology to the construction field. It is an intelligent building manufacturing mode characterized by the deep integration of information integration technology and digital manufacturing technology. This building construction method has a series of advantages such as intelligence, personalization, and low emissions, and is an ideal building model for future buildings. At present, the development and application of 3D printing building technology is still in the primary stage, and there is little research on the mechanical properties of various 3D printing building components. Basing on the previous 3D printed concrete beam tests of the research group, the paper established a finite element model, carried out further parameter analysis, and focused on the influence of the characteristics of printing path and bonding surface (between the 3D printed concrete outer frame and the core area concrete) on the bearing capacity of 3D printed concrete beams. The research showed that the 3D printed concrete beam numerical model established in the paper showed a high reliability, and the load-displacement curves were basically consistent with the test results; the beams with rotary printing path showed a higher bearing capacity; and the bonding characteristics between the core area and the 3D printed outer frame had a significant impact on the bearing capacity of the beams. Improving the bonding strength of the bonding surface could effectively improve the ultimate bearing capacity of 3D printed concrete beams.