The traditional surgical navigation system for open liver tumor resection has some problems, such as low tumor localization accuracy, high complexity of system operation, and heavy surgical burden on surgeons. To solve these problems, this paper proposes an augmented reality surgical navigation system based on coaxial projection of surgical paths. Firstly, the intraoperative tumor localization module is used to locate the tumor. An augmented reality coaxial projection module for surgical path projection has been developed. In addition, a unified view of the camera and projector in the module is designed. Secondly, we propose an algorithm for image registration and fusion. The actual scene image of the liver captured by the augmented reality coaxial projection module is registered and fused with the model image to determine the tumor’s location in the surgical image. Then, surgical path planning is carried out for the tumors in the surgical images. An augmented reality coaxial projection module projects the surgical path onto the surface of the liver to assist surgeons in tumor resection. Finally, we validate the performance of our proposed surgical navigation system through multiple sets of experiments on tumor resection. The experimental results show that the average error and time of tumor resection based on this system are 2.95 mm and 59 s, respectively. It can be seen that the system proposed in this study achieved better results under laboratory conditions. The development of this system lays the foundation for our future research in clinical surgical navigation systems.