Phase change cooling vests effectively reduce heat stress in highly insulating chemical protective clothing. However, the standard test method, ASTM F2371, uses a static sweating thermal manikin, which may not reflect real-world movement. This study investigates the effects of sweat and movement on vest cooling efficiency. A thermal manikin was tested in a climate chamber (35 ℃, 60% RH, 0.4 m/s wind) under four conditions: Static_Dry, Static_Sweat, Walk_Dry and Walk_Sweat. Measurements included micro-environment temperature, humidity, manikin skin temperature, and vest cooling power. Results showed that Walk_Sweat mode enhanced cooling efficiency by 105.6% over the Static_Dry baseline, with Static_Sweat and Walk_Dry improving it by 81.2% and 12.9%, respectively. Movement enhanced air flow and heat homogenization, while sweat evaporation significantly influenced the micro-environment, even in high-isolation clothing. These findings analyze factors influencing the cooling efficiency test method for phase change cooling vests using a thermal manikin, providing insights to improve test method and optimize vest designs.