The tethered drone emergency lighting system mainly consists of the drone, tether box, onboard power supply, and floodlight. The tether box integrates an AC/DC converter, tether cable, cable retraction and deployment device, servo motor, communication module, heat dissipation system, and control and management system. The tether box converts AC power provided by power supply equipment such as mains power, generator, or mobile power supply into high-voltage DC power, which is transmitted to the onboard power supply through the tether cable. The onboard power supply converts the high-voltage DC power into low-voltage DC power to power the drone and mission payloads such as floodlight, enabling up to 12 hours of uninterrupted flight.