The effects of organic fertilizer substitution for chemical fertilizer in dryland potato production on the yield and efficiency were explored to provide a theoretical basis for chemical fertilizer reduction and efficient resource utilization. The effects of different organic fertilizer nitrogen substitution of 25% (T1)，50% (T2)，75% (T3) and 100% (T4) of chemical fertilizer nitrogen on potato yield，water use efficency and nitrogen utilization were studied in 2020-2021，using chemical fertilizer alone(CF) as control. The results showed that the T1 and T2 treatments increased potato yield and yield components such as individual potato weight and commercial potato weight，and increased potato water use efficiency，nitrogen fertilizer bias productivity，nitrogen fertilizer agronomic efficiency and nitrogen fertilizer utilization. Compared with CF treatment， potato yield and water use efficiency increased by 5.5% and 5.4%，4.1% and 4.2%，respectively，and nitrogen fertilizer bias productivity，nitrogen fertilizer agronomic efficiency and nitrogen fertilizer utilization increased by 5.5% and 5.4%， 12.6% and 12.5%，12.1% and 8.3%，respectively，in T1 and T2 treatments. The combined yield，water use efficency， nitrogen utilization and curve fitting analysis showed that organic fertilizer equivalent nitrogen replacing 36%-46% of chemical fertilizer nitrogen was the best fertilizer application rate to achieve efficient potato cultivation under full film cover monopoly planting conditions in the semi-arid northwest.