To support end-to-end QoS (Quality of Service) in wireless multi-hop networks, a modified 2-Dimensional tandem Queuing Model (2DQM) is proposed with cross-layer design. This model exploits the traffic arrival process, multi-rate transmission in the physical layer and error recovery technology with the protocol of truncated ARQ (Automatic Repeat Request) in the data link layer. Based on this model, QoS metrics of wireless links can be evaluated hop by hop. In addition, the model has a distributed nature, which can be applied to the route discovery for QoS routing. Simulation results indicate that the proposed model can estimate the end-to-end packet loss-rate and average delay more accurately. Compared with the Minimal Hop Routing (MHR) algorithm, the model based routing algorithm can find routes with better QoS performance (with lower end-to-end packet loss-rate and delay), and better satisfy the QoS requirements of applications.