Mobile sink brings new challenges to densely deployed and large wireless sensor networks (WSNs). When the sink moves, frequent location updates from the sink can generate excessive power consumption of sensors. In this paper, we propose IAR, an Intelligent Agent-based Routing protocol that provides efficient data delivery to mobile sink. Proposed algorithm reduces signal overhead and improve degraded route called triangular routing problem. We have evaluated IAR performance through both mathematical analysis and simulation experiments. The results show that our scheme effectively supports sink mobility with low overhead and the improvement of triangular routing problem¹.