Abstract: Numerous factors may affect the longitudinal deformation of river-crossing tunnels, and one of them is the riverbed scour and siltation. Qianjiang River has great annual and seasonal changes. For the case of Qianjiang Tunnel, on the basis of the Winkler model and the elastic foundation beam, a method for analyzing the influence of the riverbed scour and siltation on the river-crossing tunnel is proposed. By comparisons with the results from the model tests, the rationality of the proposed method is proved. The further discussion on the deformation characteristics of Qianjiang Tunnel is carried out under the most unfavorable conditions, and it may provide theoretical basis for the engineering practice.