The method of bearing forced displacement is a control method used in the construction of steel girder bridges, which can largely adjust the position and angle of the bridge closure joint. However, there is currently no detailed theoretical study on the application of this method to the structural system before and after the transformation. In view of this , this paper takes a three-span continuous beam bridge under uniform load as the research object and, based on the Euler-Bernoulli beam bending differential equation, uses the integration method to solve the closed-form solution of the three-span continuous beam bridge under uniform load by using the bearing forced displacement method in two different conditions: the bridge constructed and closed step-by-step and the bridge constructed at one-time. The theoretical calculation results show that the obtained beam deflection functions under the two conditions are completely the same, indicating that under the elastic state, the three-span bridge with the bearing forced displacement method can achieve the ideal effect of one-step construction. Furthermore, this paper combines the practical application of the bearing forced displacement method in the construction of a three-span continuous steel truss bridge with the measured bridge deflection data and finite element calculation results before and after the application of the method, and the two are in good agreement, verifying the practical control effect and engineering application of the proposed method.