Heat release rate is the most essential parameter for combustion process,and often employed to study the dunamic supression process of a pool fire under water mist application.Based on oxygen consumption theory,cone calorimeter is widely used to measure the heat release rate of a fire. However, one of the main simplifying assumptions of this technique is that the incoming gases into the susten only come from ambient atmosphere.When water mists are applied to the pool fire.some of them would be heated and evaporate into water vapor,so the incoming gas concentration would be affected ,resultig in signifecant bias of the heat release tate measurement.In this paper a simple method to reduce this effect due to water vapor was develped and the heat release rate of the pool fire interacted with water mists was studied using the cone calorimeter.The factors such as pool scale,fuel type and water mist volume flux were considered in the experiments.The heat release rate was reduced signifcantly when water mists of adequate flux were applied to the pool fire,and however was enhangced with water mists of small quantity .As regards to some incomplete combustible fuel sample,the enhangcement effect was obvious.