In order to study the influence of piston speed, temperature and low temperature on the power and dynamic characteristics of the yaw damper, experimental analysis was done on the yaw damper used in China railway EMU. The test results show that：at low temperature (less than -10 ℃), yaw damper power changes with temperature; at high temperature, yaw damper power changes little with temperature; when the yaw damper piston is running at low speed, the temperature change has great influence on the dynamic damping; when the yaw damper piston is running at high speed, the temperature change has a great influence on the phase angle; the sustained temperature rise of the yaw damper has a great influence on the performance of the yaw damper at low temperature, and the effect of temperature rise on the performance of the yaw damper at room temperature is not significant.