The wireless sensor network (WSN) is a typical networked embedded system. It involves in both embedded systems and networks, and is extraordinarily application-specific; therefore testing and debugging WSN becomes relatively complicated with various difficulties. Developing a one-fits-all platform for WSN testing and debugging is difficult to achieve. In order to efficiently test and debug the implementation of WSN application, this paper carefully analyzed previous related researches, adopted the half-practicality simulation strategy, proposed a hybrid testing and debugging system for WSN, and solved the problems that pure software simulation veils too many hardware implementation details and in-situ platforms can only provide limited visibility and controllability for both the embedded systems and the networks, thus achieved a balanced achievement. At last, an instance platform of the hybrid testing and debugging system for WSN was implemented in the field programmable gate array (FPGA); experimental results verified the correctness and validity of the proposed system.