Purpose <p>When interaction region magnets operate under high current density, any failure in the water-cooling system can lead to rapid coil temperature rise, posing a serious risk of burnout. A specialized thermal protection system—distinct from conventional analog approaches—is required to mitigate this risk.</p> Method <p>This paper proposes a novel digital thermal protection system that detects temperature-related resistance changes via voltage measurements across the coil, utilizing the positive temperature coefficient of copper. The protection logic is implemented in a field-programmable gate array (FPGA) embedded within a CompactRIO (C-RIO) platform. In addition, real-time voltage data from 136 coil channels are transmitted via TCP/IP to a central monitoring computer, enabling fault diagnosis and system analysis.</p> Results <p>The system has been rigorously tested and successfully deployed at the Beijing Electron–Positron Collider II (BEPC-II). It achieves a fast response time that meets upgrade requirements, and all protection parameters are configurable via software. Experimental results—such as response time and filter performance—demonstrate that the system fulfills its design objectives.</p>