In practical engineering applications, structures typically exhibit a rigid-flexible coupled vibration effect, resulting in large nonlinearities in structural components and load identification accuracy being greatly affected. Since most load identification methods do not consider structural flexibility, this paper based on Simpack to establish a flexible beam to consider the multi-body coupling vibration effect of the beam structure, and simulate and experimentally study the load identification. Firstly, the multi-body dynamic model of flexible cantilever beam is established, and the coupling vibration response of the beam under concentrated dynamic load is obtained. Secondly, the truncated singular value decomposition (TSVD) regularization methodis selected to solve the flexible body load equation and find the optimal solution of the equation. Finally, through numerical simulation, the identification results of flexible beam structure under different loads are analyzed, and the effects of different noise levels and different response data on the identification results are discussed. The results show that for the flexible beam, the method can accurately identify various forms of loads on the structure by using the displacement response and velocity response, but the identification effect is not ideal for the sudden change load such as square wave load, and it is easy to be affected by noise. Additionally, it should be noted that using acceleration response data to reverse calculate the load results is poor.