The motion of the tumor limits further improvement in the accuracy of radiotherapy. Real-time monitoring and tracking of tumor location is an emerging technology to improve the accuracy of tumor radiotherapy. According to the adopted methods, it can be broadly divided into non-radiation-based and radiation-based systems. The former system includes ultrasound guidance, nuclear magnetic resonance guidance, electromagnetic tracking, optical image guidance, artificial intelligence-based technologies, and the latter system consists of KV, MV-grade X-ray imaging system and CT-based guidance system. In this review, research progresses on real-time tumor monitoring and tracking technology in radiotherapy, respective advantages and disadvantages and current clinical application were summarized.