In power system, dry-type air-core reactor usually works in high-voltage environment and its own short-circuit and open-circuit faults are the main fault factors of dry-type reactor at present. In order to solve the problems of low detection sensitivity, measurement delay and easy misjudgment of dry-type reactor fault, an online monitoring system for dry-type reactor edge based on split-phase transverse differential protection is proposed in this paper. This paper discusses the structure of the edge monitoring system based on the star-arm currents split-phase transverse differential protection of the dry-type air-core reactor, it designs the software and hardware systems required by the edge monitoring system, such as energy acquisition, current acquisition and data analysis and processing modules. The effectiveness of the proposed method and system in the short-circuit and open -circuit fault monitoring of dry-type air-core reactor is verified through experiments.