Abstract: 【Objective】This study aimed to establish a technical and theoretical foundation for ecofriendly potato cultivation in the dry farming regions of central Gansu Province.The research focused on elucidating the primary mechanisms underlying the substitution of organic fertilizers for chemical fertilizers concerning photosynthetic characteristics and antioxidant enzyme activity.【Method】Four distinct treatments were implemented:sole application of chemical fertilizer （T₁）,50%substitution of organic fertilizer for chemical fertilizer （T₂）,25%substitution of organic fertilizer for chemical fertilizer （T₃）,and a control group without fertilizer （T₄）.The impact of these treatments on potato growth,photosynthetic physiological traits,and yield was investigated.【Result】The T₂ treatment notably enhanced potato growth.Within the substitution regime,the leaf area index,chlorophyll a,chlorophyll b,and total chlorophyll content significantly increased by 112.5%,50.82%,82.86%,and 57.59%,respectively,compared to the no-fertilizer treatment T₄.Organic fertilizer substitution augmented the superoxide dismutase activity during tuber swelling and starch formation stages while reducing malondialdehyde levels.Yields rose by 7.89%to 28.37%compared to T₁ and T₄ treatments devoid of fertilization.【Conclusion】Through the optimization of the interplay among leaf area index,chlorophyll levels,and photosynthetic traits,the T₂ treatment with a 50%replacement ratio of organic fertilizer for chemical fertilizer bolstered antioxidant enzyme activity in leaves,delayed plant aging,and heightened photosynthetic efficiency and effective dry matter transport,ultimately enhancing yield.In summary,a 50%substitution of organic fertilizer for chemical fertilizer emerges as the suitable scientific replacement ratio in this region.