Aiming at the low irrigation efficiency of farmland irrigation and drainage system layout in Hetao Irrigation District, this paper explored the suitable design scheme of border irrigation under changing environment. This paper analysed the state of water flow movement, irrigation performance, and cost-effectiveness by carrying out the fine horizontal irrigation field experiment under different widths. The results showed that:(1) Different widths have great influence on soil infiltration depth and irrigation performance. When the width of the border was large, the water flow advancement time was prolonged, and the water depth of the furrow head infiltration increased, resulting in poor overall irrigation effect. By 10~15 m, the effective water use efficiency and irrigation uniformity increased by 11.96%~20.61% and 2.49%~5.95%, respectively, and the irrigation performance was significantly improved. When the width was reduced to 5 m, the relative flow rate of the single inlet increased. Irrigation water accumulated in the furrow tail, which increases the depth of the infiltration of the furrow tail, and the infiltration of the furrow head was insufficient, which leads to a decrease in the performance of irrigation. (2) By analysing the composition of each treatment cost and the yield benefit, it could be found that the most expensive expenditure in agricultural production is still other costs such as fertilizer, seeds, and films, accounting for more than 70% of the total plant cost. After the increase in the number of ridges, the mechanical cost increased by 0.3~4.6 times compared with the local traditional level. Although the water fee decreased slightly, the total cost T_c increased by 2.72%~9.98%. (3) When water-saving experiments were carried out, the water-saving benefits and economic benefits were usually contradictory. The water-saving and good-efficiency schemes tend to have poor economic benefits, while the schemes with poor water-saving benefits had improved economic benefits, it is recommended to increase the enthusiasm of farmers by granting water-saving subsidies to farmers in accordance with the subsidy standard of 1 095~1 665 yuan/hm² when promoting new water-saving technologies in irrigation districts. (4) In this paper, by analysing the comprehensive benefit function under the combination of different weights of economy and water saving benefits, it is preliminarily determined that when the optimization of each treatment scheme is made, if the water saving benefit is prioritized, the width should be appropriately narrowed, and if the economic benefit is prioritized, the width should be appropriately enlarged.The results should provide theoretical support for water saving reform design and sustainable development of agriculture.