Abstract: The collecting water way uses the combination of sloping plate and U-type channel for the high-level water collecting natural draft wet cooling tower（HNDWCT）. Due to the advantages in energy saving, environmental protection and economy, the HNDWCT has promising application foreground in large nuclear power plants and other engineering field.Loading the mass, momentum, energy equation by user defined function was computed in Fluent. The numerical calculation result was accurate enough by comparing with the field measurement data. Then, the influences of water mass flow rate,inlet water temperature, fill height and environmental crosswind on cooling performance of the HNDWCT were simulated numerically. It is found that environmental crosswind increased from 0 m/s to 9 m/s, the outlet water temperature increased by 5.30 K. When the environmental crosswind is more than 6 m/s, eddies appears which might damage the homogeneity of the air flow field greatly. The water ?ow rate increased by 2.53 kg/（m2 s）, the outlet water temperature improves 4.72 K. This implies the heat exchange capacity of the flow in the tower weakens with water ?ow rate and the droplet number increasing. In addition, fill height increases from1.25 m to 2 m, cooling performance improves because the increase of heat exchange area causes the increase of latent heat of evaporation although air resistance rises. Increase of water temperature improves the density difference between the inner and outer areas of the HNDWCT, which enable the pumping force and the mass and heat transfer capacity enhances.