Abstract: A variety of indoor positioning technologies have emerged, such as ultrasound, infrared, wireless local area network, bluetooth, radio frequency identification, and ultra wideband. These systems require additional hardware devices and complicated deployment. Pedestrian Dead Reckoning can provide motion information at a high update rate and achieve high precision over a short time duration, However, without external aids, the system suffers from local anomalies and cumulative error after positioning for a longer length of time. Many researchers use a step length model combined with direction information to calculate the displacement of indoor pedestrians with accuracy step counting method. A step counting algorithm based on zero-velocity update was proposed. By analyzing the pedestrian's moving character and posture, acceleration amplitude measurement used to detection the movement stage of pedestrian was employed to calculate steps with Micro Electro Mechaical System (MEMS). The experimental results show that the scheme proposed in this paper was high precise and had good adaptability to different motion state, reporting accurately more than 98% overall, which is appropriate for complex indoor environment.