We consider the problem of flow control using incentive strategy in Stackelberg game theory. The network model employed here is that users route their flows from a common source to a common destination node, each of them trying to optimize its individual performance objective. First, the existing Stackelberg routing strategy is briefly introduced. And then, the linear Stackelberg incentive strategies are presented for both single-follower and multi-follower systems, by which the leader (manager) force the followers (the noncooperative users) adopt the team optimal flow configuration as their reply strategies. We show that our incentive strategy improves the existing Stackelberg routing strategy. A numerical example is given to illustrate our results strategy.