The strain method is one of the commonly used methods for load measurement of metal structures. The accuracy and linear correlation of the data measured using the strain method under the individual effect such as bending moment, shear force, and torque are very good. In reality, the structural stress situation is complex and structures are often subjected to coupling effects of bending moment, shear force, and torque. Therefore, the linear correlation between the data measured by the strain method and the multiple linear regression equation generated by the input load value needs further verification. A typical flexural?torsional beam structure is designed. Under the coupling effect of bending moment and torque, the strain method is used to measure the load. The accuracy of the measurement data is good, and the linear correlation of the multiple linear regression equations generated by multiple variables such as input load value, bending moment and torque is strong.