The impact on construction period is ignored in all existing research results on wind load of cooling towers. Taking the 220 m the world's highest super large cooling tower under construction as the example, the flow field information and three-dimensional aerodynamic forces during construction period are obtained based on large eddy simulation（LES） method. The validity of numerical simulation is verified through comparing the average wind pressure distribution of the entire tower with the standard curve and the measured curve. On this basis, the average wind pressure distribution and flow field characteristics under construction period are investigated. At the same time, the flow field characteristics and action mechanism are extracted from the velocity and vorticity changes of the cooling tower under different working conditions. The distribution regularities of the pulsating wind pressures and extreme wind pressures, lift/resistance coefficients and the correlations between points are revealed. Finally, the fitting formula of extreme wind pressures is given based on the nonlinear least square method. Studies show that the pressure extreme value on cooling tower firstly increases from -3.91 to -1.75, then decreases to -2.28 with the increase of construction height, the lift coefficient decreases with the increase of construction height, and the correlation of fluctuating wind loads firstly increases, and then decreases with height increase. Main conclusions can be used as reference to design wind loads on such large cooling towers during the construction.