Abstract: The weak signal of MEMS hot-film wall shear stress (WSS) sensors is hard to detect by direct amplification due to the inherent basic voltage. An effective method to solve this problem is proposed, which is to add an output-balancing system (OBS) before the signal is amplified. The basic voltage is decreased while the signal is retained. The development of the output-balancing system is presented, including the technical scheme, key technologies, examination and application.