The invention provides an external cantilever anchoring force calibration system. A central processing device, a theoretical value input end, an analysis end, a force sensor, a signal processing circuit, a temperature sensor, a comparison module and a display are used to calibrate the external cantilever anchoring force of a double-limb thin-walled pier. The theoretically calculated external cantilever anchoring force is compared with the external cantilever anchoring force measured by the sensor to know whether the external cantilever anchoring force test is accurate. The temperature information of the test site is collected through the temperature sensor, which is convenient for staff to know the on-site ambient temperature during the external cantilever anchoring force test. During theoretical calculation, the method of average wiring load conversion is used to calculate the external cantilever anchoring force. When the sensor is used to collect the external cantilever anchoring force, the measured data are more accurate through the signal processing circuit. .