The utility model provides a downhole load testing tool of a coiled tubing. The downhole load testing tool comprises an inner barrel and an outer protecting barrel, wherein the outer protecting barrel fixedly sleeves the outer surface of the inner barrel, an upper joint is arranged on the upper end of the inner barrel, a tension torque sensor is in threaded connection to the lower end of the inner barrel, and a sealing ring is arranged between the lower end of the outer protecting barrel and the tension torque sensor; a power supply module, a storage and a temperature sensor are arranged between the inner barrel and the outer protecting barrel, a pressure sensor is arranged on the inner barrel wall of the inner barrel, the tension torque sensor, the temperature sensor, the pressure sensor and the storage are respectively connected with the power supply module, and the tension torque sensor, the temperature sensor and the pressure sensor are respectively connected with the storage. According to the tool, four parameters of tension, torque, temperature and pressure of the coiled tubing can be measured by descending the tool once, the downhole load of the coiled tubing can be effectively detected, mechanical properties of tube strings are stored and recorded, the stress change of tube columns is analyzed, and mechanical operation states of tripping, fracturing, drilling polishing, well repair and the like of the tube strings are recorded.