Abstract: Abstract In the context of sustainable agricultural development, fertilizer reduction and efficiency have become key issues. This study focuses on the effects of moderate reduction of phosphorus fertilizer application on the physiological characteristics and material production capacity of potato leaves, aiming to explore effective ways to enhance potato yield and economic benefits. A phosphorus fertilizer reduction experiment with different gradients was set up in Dazui Village, Haiyuan County, Ningxia, in 2018-2019, with the customary phosphorus application by local farmers (240 kg·hm^-2, RP) as the relative control. Four phosphorus reduction treatments were set up: P25 (180 kg·hm^-2, 25% reduction), P50 (120 kg·hm^-2, 50% reduction), P75 (60 kg·hm^-2, 75% reduction), and CK (0 kg·hm^-2, no phosphorus fertilizer as the absolute control), to systematically monitor the changes in the functional indexes of the leaves and the characteristics of the dry matter accumulation of the potato and to analyze the correlations between these changes and the yield and economic benefits. and economic benefits. Adequate phosphorus reduction can effectively optimize the functional characteristics of potato leaves, with P50 treatment having the best effect. Specifically, LAI (leaf area index), Pn (net photosynthetic rate), Ci (intercellular CO₂ concentration), Gs (stomatal conductance), Tr (transpiration rate), Chla (chlorophyll a), Chlb (chlorophyll b) and Car (carotenoids) were increased by 34.39%, 8.28%, 1.26%, 5.39%, 30.27% and 1.26%, respectively, in the P50 treatment compared with RP, 5.39%, 30.27%, 30.75%, 25.08% and 28.80%, respectively, and delayed the arrival of leaves at the onset of senescence by 2.26 d. It was also able to significantly increase the antioxidant capacity and osmotic regulating substances of potato leaves, and inhibit the expansion of cellular membrane permeability and the accumulation of MDA; at the same time, it was able to significantly increase the maximum dry matter accumulation rate (G_max) and the average accumulation rate (G_mean). The potato yield of the moderate phosphorus reduction treatments did not decrease due to the reduction of phosphorus fertilizer dosage, and some treatments even increased with P50 performing the best, followed by P25. Principal component analysis showed that the composite scores of all treatments were P50>P25>RP>P75>CK. 50% phosphorus reduction (120 kg·hm^-2, P50) continued to improve the physiological characteristics of potato leaves and optimize the dry matter accumulation characteristics compared with the other treatments, and was able to maximize the potato yield and commercial potato yield. Therefore, 120 kg·hm^-2 of phosphorus application in this experiment can be taken as the recommended phosphorus application rate for reducing phosphorus and increasing efficiency of potato in the semi-arid region of Northwest China, so as to achieve the purpose of green and high-yield cultivation.