The invention discloses a proportional fairness spectrum resource allocation method based on a multi-hop hybrid backhaul network. The method comprises the following steps: layering a base station, and redesigning a frame structure; constructing a generalized objective function of proportional fairness resource allocation based on utility functions of proportional fairness; deriving an optimal solution of spectrum resource allocation by using a Lagrangian multiplier method and an iterative algorithm; and calculating optimal access resource blocks and backhaul resource blocks for each layer of the base station. According to the method disclosed by the invention, the objective function is constructed based on the utility functions of proportional fairness, the most optimized spectrum resource allocation result is derived, and thus the overall throughput of the system can be effectively increased under different scenes, and the fairness of users can be guaranteed; and the method is suitable for resource allocation of base station backhaul links and access users in a multi-hop hybrid backhaul network under an ultra-dense networking scene, can realize the plug-and-play deployment requirements of ultra-dense networking, and has wide application and promotion values.