Offshore wind power converter is usually packed in a closed cabinet equipped with water cooling to meet the moisture and salt spray prevention requirements. When a sudden dip of wind speed happens, the generated power will reduce significantly, making power semiconductor device and cooling water’s temperature reduced quickly. While the air temperature inside cabinet decreases slowly. Thus, the water-cooling panels and water pipes become cold spots. When the temperature is below the dew temperature, the condensation will happen. In this paper, the reactive power oriented thermal control is proposed, which controls the reactive power circulating between the two parallel wind power converters to prevent condensation. The circulating reactive power controls the power semiconductor and water-cooling panels’ temperature above the dew temperature. In this paper, the reactive power oriented thermal control and anti-condensation method are analyzed. Finally, the MATLAB/PLECS simulation is carried out to validate the feasibility of proposed method.