Abstract: The iGrav superconducting gravimeter is the newest relative gravity meter with the highest accuracy and most portable measurements in the world. It provides the most stable relative gravity measurement. The calibration factor for the iGrav-007 superconducting gravimeter was accurately determined using site observations obtained with the FG5-112 absolute gravimeter and the iGrav-007 superconducting gravimeter at Wuhan Jiufeng station,based on Least Square method. The data processing results show that the calibration factor was(-91.640 2±0.085 2)×10^-8 m·s^-2·V^-1 with a relative calibration accuracy of 0.092 9%, the accuracy of the calibration factor obtained by the absolute gravimeter for one day was better than 0.2%, the accuracy of the calibration factor obtained by absolute gravimeter for three days was better than 0.1%.