Abstract: An adaptive beam string structure was a form of an intelligent structure, which can control the working status by adjusting the prestress of the structure according to the changes of external loads. Firstly, the working mechanism of the structure was analyzed. Next, the equations of structural force status were established. And then the force control problem of slack of the lower chord cable caused by the negative air pressure was analyzed, and the corresponding control model was built. Furthermore, the force control problem of the inhomogeneous internal force of an upper chord beam caused by moving loads was analyzed, while the load space was divided into controllable regions with a time lag or not according to the magnitude and the moving velocity of moving loads. The control model of each controllable region was built respectively for optimising structural force status. Finally, a numerical example was conducted to verify the working performance of the structure. Numerical results demonstrate that: in the comparison with a normal beam string structure, an adaptive beam string structure can reduce the peak force and initial prestress level as well as improve bearing capacity by adaptive control.