Today's researchers are witnessing the evolution of multi-interface terminals. The simultaneous utilization of multiple interfaces to improve network performances is facing a great challenge. The multiple interfaces are usually heterogeneous and wireless with different link characteristics. Because of unreliable wireless links, we need a good description of link characteristics. Kalman filter is an efficient recursive method which not only estimates and corrects the current system states but also predicts even the future states based on the latest state. In this paper, we use Kalman filter to predict packet transmission delay and use this estimation result for the flow distribution algorithm of concurrent multipath transfer. The simulation results show that our proposal with Kalman filter reduces the reordering degree and improves congestion window growth pattern. As a result, the total goodput increases.