Abstract: Based on the principle of profit maximization in neoclassical economics, 771 apple growers samples in the apple predominant area of the Loess Plateau were used to analyze the market incentive effect of farmers' commercial organic fertilizer input and the regulatory effect of farmland confirmation in the incentive effect. The results show: (1)Farmers' commercial organic fertilizer input is simultaneously stimulated by the agricultural product market and the farmland market, both the apple market and the farmland market have an effective incentive effect on the commercial organic fertilizer input of apple growers in the Loess Plateau; (2)The market incentive effect of apple market on commercial organic fertilizer input of apple growers is higher than that of farmland market; (3)Farmland confirmation has a positive regulatory effect on the incentive effect of farmers' commercial organic fertilizer input in farmland market. This study extends the theoretical interpretation of the farmers' protective investment behavior for farmland by neoclassical economics, and provides a reference for how to effectively encourage farmers to increase the application of commercial organic fertilizer.