The Lanzhou-Xinjiang High-Speed Railway passes through regions frequently affected by strong winds. Although the construction of wind-break walls can effectively ensure train safety, it exacerbates the galloping of the catenary positive feeder. To suppress the galloping of the positive feeder, this paper establishes a three-dimensional flow field model of wind-break walls with different wall top structures and perforation types based on fluid dynamics theory, and optimizes the design of the wind-break wall structure. The results show that different wall top structures of the wind-break wall alter the flow field around and behind the positive feeder line, reducing wind speed at the wire and decreasing the extent of the high-speed wind zone. When the gap ratio of the city wall-type wind-break wall is 0.5, the lift coefficient and drag coefficient of the positive feeder line decrease by 26.40% and 12.13%, respectively. The larger the porosity of the wind-break wall, the smaller the extent of the high-speed wind zone behind the wall, and the lower the wind speed. The reduction in wind speed at the positive feeder line is significant, and the airflow tends to stabilize. Under the circular perforated wind-break wall with a porosity of 0.4, the lift and drag coefficients of the positive feeder line decrease by 51.15% and 45.59%, respectively. By reasonably designing the wind-break wall structure, the galloping of the positive feeder can be effectively suppressed.