Objective To study the characteristics of nitrogen(N), phosphorus(P) and potassium (K) nutrient release and soil N, P, K nutrient balance under straw mulching pattern during potato planting process.Method We studied the decomposition rate and nutrient release status of mulching straw using pot experiment.Result Straw carbon (C) and P contents changed slightly after mulching for 82 days, while K content decreased by 93.96%, and N content increased by 49.22%. The mulching straw provided a large amount of nutrients (especially K) with 100 kg mulching straw contributing 0.42 kg N, 0.14 kg P (P₂O₅), and 1.70 kg K (K₂O) to soil used for potato growth. Straw decomposition rate was 70.87%. The nutrient accumulative release rates were performed as: K (98.22%) > C (71.89%) > P (68.75%) > N (56.85%). Straw mulching and K fertilization largely affected soil K balance. The K deficient amount was 163.80 kg/hm² without straw mulching and K fertilizer application. K deficient amount was effectively reduced by straw mulching and K fertilization, and even K had surplus with combined application of straw and K fertilizer.Conclusion The straw mulching pattern can reduce K fertilizer application amount and production cost, and relieve the dilemma of K fertilizer resource deficiency in China.