A drag-reduced conductor has advantages of reducing the wind load on the conductor and the wind pressure on the transmission line tower. Previous studies found that changing the parameters of the drag-reduced conductor cross-section groove will have a certain impact on the wind resistance of the conductor, but there is no in-depth study on the specific optimization of conductor cross-section structure. In this paper, four kinds of drag-reduced conductor with different cross-section shapes are taken as the research objects, and the variation of wind resistance coefficient in different wind speed sections is explored in a wind tunnel test. The correlation between wind resistance coefficient and cross-section structure parameters is analyzed using polynomial surface fitting based on least squares. The results show that in the low wind speed range of 10 m/s~20 m/s, the wind resistance coefficient increases linearly with the increase of conductor cross-section roughness. In the middle and high wind speed range of 20 m/s~60 m/s, the wind resistance coefficient of the conductor is determined by the bivariate quadratic function composed of the number of grooves and the radius of grooves. By solving the minimum value of the function, the optimal section structure parameters of the conductor with low wind resistance can be obtained. Based on the Navier Stokes equation, the flow field changes of the optimized wire model and the ordinary low wind resistance wire model in multiple wind speed segments are simulated in COMSOL finite element software. This verifies the effectiveness of the fitting results. This work is supported by the National Nature Science Foundation of China (No. 51707113).