In the in-situ calibration of rotor balance, the calibration uncertainty is the most important technical factor. First, the environment according to the actual working condition and in-situ calibration method is studied. Then, the in-situ calibration device was developed, mainly introducing the mechanical structure design and ascertaining the sources of uncertainty. Finally, for the first time in-situ calibration test of the rotor balance was completed and for in-situ calibration uncertainty was evaluated in accordance with the standard method. The results showed that the standard calibration device has achieved that the relative force-component calibrating uncertainty is better than 0.1%, the relative torque component calibrating uncertainty is better than 0.3%.