Wireless sensor networks, due to their potentially wide application perspectives, may proliferate in future. Two major stumbling blocks are the dynamic variance of network topology caused by the energy constraint of sensor nodes and uncertainties of wireless links, and the security routing in this severe security environment. Therefore adaptable and defendable routing mechanism is in urgent need for the deployment of these networks. In this paper, we propose FBSR, a novel feedback based secure routing protocol. Feedback, from both the nearby neighbors and base stations, serves as the dynamic information of the current network, with which sensor nodes make forwarding decision in a secure and energy aware manner. We present both mathematical analysis and simulation results to show the efficiency of FBSR.