Disruption Tolerant Network (DTN) attempts to transfer messages via intermittently connected nodes. The difficulty lies in that the routing connectivity is opportunistic, and the network topology information is lacking between nodes. Spray and Wait is an efficient routing scheme in such environment, it "sprays" a number of copies into the network, and then "waits" till one of these nodes meets the destination. Compared with epidemic routing, Spray and Wait consumes less network resources, but still suffers from severe contention under high network load. Therefore, based on the analysis of Spray and Wait routing, an ACK-mechanism was used to remove the redundant messages which lead to less network resource consumption. Meanwhile, token forwarding was adopted in order to improve the bandwidth utilization. The improved routing scheme was simulated on ONE platform and the simulation results show that it has higher average delivery rate and consumes fewer network resources though it has slight higher average delivery delay. The scheme works well in intermittently connected mobile networks without any priori connectivity knowledge.