As the central point of failure, sink location protection is critical to the viability of the whole sensor network. However, existing work related to sink location protection only focuses on local traffic analysis attack. In this paper, we examine the sink location protection problem under a more powerful attack, the global traffic monitoring attack for the first time. In order to hide the sink location, a scheme based on packet sending rate adjustment (SRA) is proposed. By controlling the packet sending rate of each node according to the current number of source nodes, SRA conceals the real traffic volume generated by new source nodes and hence disguises the location of the sink. Theory analysis shows that SRA can protect the sink location against global traffic analysis attack effectively. Simulation results demonstrate that SRA has low communication cost and acceptable end-to-end latency.