Carbon Capture, Utilization and Storage-Enhanced Oil Recovery (CCUS-EOR) is currently the most pragmatic, effective, and feasible carbon emission reduction technology, but there are risk of CO2 leakage during the actual operation of the project. In order to ensure the effectiveness of CO2 flooding and safety of the system, it is necessary to monitor, evaluate and provide an early warning for the entire process operations including CO2 injection, oil displacement, CO2 storage, oil recovery, gathering and transportation, CO2 reinjection, etc. Through the literature research on more than 100 domestic and international CCUS-EOR projects, the characteristics, application scenarios and problems of various monitoring techniques are systematically analyzed. The progress of CCUS monitoring and early warning technology, both at home and abroad, is summarized from the perspectives of monitoring system and key technologies. At the same time, the development trends of CCUS-EOR monitoring and early warning technology are identified. Finally, suggestions are put forward in order to promote the development of CCUS-EOR, including developing an improved and refined monitoring system, developing key equipment, deepening the research of digital intelligence technology, and building an industrial internet platform.