Abstract: In order to solve the problem of the strain surge in the composite material vertical-tail strain bridge, a physical model for measuring the flight load of the composite material wing structure by the strain method is established, and the qualitative verification test is carried out. The theoretical analysis and the experimental results show that the strain of the two bending moment bridges increases sharply (the strain values are 175.24 and 254.15, respectively) while the strain values of the two shear bridges change but little (the strain values are 13.52 and 3.83, respectively) , because of the heterogeneity of the composite, and the fact that the thermal strain is amplified by the thermal conductivity and the distance between the two strain gauges to make up the bridge. This result provides a theoretical basis for the measurement of the composite load in the thermal environment by the strain method.