The axial force of braces is an important index to verify the safety of foundation ditch supporting system, and it is of great significance to the safety judgment of foundation ditch during construction. But the monitoring data of the braces axical force in the field is obviously divorced from reality, and the axial force data monitored often exceeds the actual safety design value several times, so it is difficult to be an effective indicator of safety monitoring. Considering the influence of non-load factors on the strain data of reinforced concrete support, the CEB90 model is chosen as an example to correct the strain, and the corresponding calculation theory and method are put forward. The axial force of the actual support monitoring data is corrected, and the axial force changes before and after the correction are compared. The results show that the non-load factors have a great influence on the axial force monitoring, which indicates that the non-load factors should be considered in the monitoring of the axial force of the reinforced concrete braces.