The invention provides a coiled tubing underground load testing tool. The tool comprises an inner cylinder and an outer protecting cylinder fixedly arranged on the outer surface of the inner cylinder in a sleeving mode, wherein an upper connector is arranged at the upper end of the inner cylinder, a tension and torque sensor is connected to the lower end of the inner cylinder in a threaded mode, and a sealing ring is arranged between the lower end of the outer protecting cylinder and the tension and torque sensor; a power module, a memory and a temperature sensor are arranged between the inner cylinder and the outer protecting cylinder, a pressure sensor is arranged on the wall of the inner cylinder, the tension and torque sensor, the temperature sensor, the pressure sensor and the memory are all connected with the power module, and the tension and torque sensor, the temperature sensor and the pressure sensor are all connected with the memory. By the adoption of the tool, the tension, torque, temperature and pressure of a coiled tubing can be measured by placing the tool underground once, the underground load of the coiled tubing can be effectively detected, the mechanical property of pipe strings can be stored and recorded, stress change of drill strings can be analyzed, and the mechanical states of pipe strings during tripping operation, fracturing, drill-polishing and well repairing can be recorded.