The finite element analysis simulation of the joist load testing and the substrate FBG sensor was performed in this paper.The substrate FBG sensor with certain prestretching force loaded was fabricated and packaged.The experiment on the calibration was carried out to compare the prestretching substrate FBG sensor with the bare FBG sensor in MTS.The results showed that the measurement range of the sensor fabricated the prestretching process was improved,the strain sensitivity was of 0.95 pm/με,linearity was 0.996,and the transfer efficiency was 83.5%. The load testing was applied to the joist of airplane wing,while using the resistance strain gauge was used to monitor the maximum strain,good test results were obtained and consistent with the simulation results,which was of great significance for the calibration of aircraft wing loading.