In this paper, we propose MWTP (Multi-hop Waiting Time Priority) scheduler to guarantee proportional delay differentiation in a multi-hop wireless network with contentionbased MAC protocol. The existing single-hop delay differentiation schedulers can not differentiate the contention delay suffered at multi-hop links, and whole delay differentiation accuracy is destroyed in the multi-hop wireless communications. MWTP marks packets with departing time at the upstream node to decide scheduling order at the downstream node. The marked departing time becomes a reference point of waiting time in the scheduling process. Analysis and simulation results support that MWTP guarantees more accurate delay differentiation than existing schedulers.