A mathematical model for predicting sprinkler cooling effect on smoke layer was developed. Results of calculation showed that the temperature difference between droplets and smoke layer and the thickness of smoke layer are major factors of the cooling effect. The cooling effect might lose its efficiency when the sprinkler pressure became relatively high. Experiments were carried out to validate the model and compared with Morgan model. The experimental results show that temperatures predicted by the current model agree well with the experimental results when temperature difference is high. However Morgan model is more suitable for low temperature difference.Copyright © 2009 by ASME