Abstract—Based on the enthalpy difference theory and the characteristics of the mechanical draft cooling tower, a mathematical method of the cooling tower performance is derived to analyze the influence of operating parameters on tower outlet water temperature. The results show that the influence of atmospheric pressure and dry-bulb temperature on the tower outlet water temperature is negligible. The wet-bulb temperature is the main environmental factor affecting the cooling tower performance. Cooling water flowrate, condenser heat load, failure cooling area and draft resistance all have a positive correlation with tower outlet water temperature. While the air flowrate of the fan increases, the tower outlet water temperature will decrease. The above conclusions will help to accurately predict the changing trend of tower outlet water temperature under variable operating conditions, and provide guidance for the adjustment of cooling tower operation under variable conditions.