Abstract: In order to calibrate the terahertz detector to ensure its accuracy and reliability of measurement, the calibration technology for responsivity of terahertz detector was studied. For commonly used blackbody radiation test technology for terahertz detector, there have been several problems such as high requirements on the environment, equipment and the difficulties in establishment. Taking the thermoelectric terahertz detector developed by the National Institute of Metrology as a standard detector, a calibration scheme was proposed and a responsivity calibration system for terahertz detector was designed and established. To improve the calibration accuracy, the beam quality of the calibration optical system was experimentally tested and the diaphragm aperture was set reasonably to meet the calibration requirements. At 0.1 THz, the responsivity of two field-effect self-mixing terahertz detectors were calibrated. The results show that the relatively extended uncertainty is 6.80% (k=2), verifying the feasibility of the calibration system. In the system, the power responsibility of terahertz detector can be traceable to the National Terahertz Power Standard and ensure the accuracy and reliability of terahertz power measurement.