In a project for monitoring the health of ultra-low temperature wind tunnel structures， the light grating sensor is used to monitor the deformation of the wind tunnel body in real time. However， the environment of ultra-low temperature and wide temperature range greatly affects the accuracy of strain measurement. In order to solve the temperature influence of strain measurement of fiber Bragg grating （FBG） sensor from -196 °C to normal temperature range and further improve the measurement accuracy， this paper proposes a strain sensitivity coefficient calibration method， which measures the strain sensitivity coefficient of FBG sensor at multiple temperature points from -196 °C ~ 20 °C through a set of ultra-low temperature wide temperature domain calibration system. Moreover， the calibration result is used to correct the ultra-low temperature wide temperature range. The measurement result of the temperature corresponding to the environment can effectively improve the strain measurement accuracy of the fiber grating sensor. The experimental results also show that the strain sensitivity coefficient of FBG sensor increases with the decrease of temperature. This conclusion lays an important foundation for further research on temperature compensation of FBG strain sensor in ultra-low temperature wide temperature range environment.