Abstract: Moderate-scale operation of agricultural land is a key path to advancing agricultural modernization and safeguarding national food security. Clarifying the relationship between moderate-scale agricultural land operation and grain yield per unit area is a crucial issue for balancing high-quality agricultural development and food security. This paper is based on provincial-level data from 19 major corn-producing provinces covering the period from 2009 to 2023, this study employs a fixed-effects model with Driscoll-Kraay robust standard errors to examine the impact of large scale operation of agricultural land on corn yield and empirically tests its moderating effects. The findings are as follows: (1) There is a positive U-shaped nonlinear relationship between large scale operation of agricultural land and corn yield, with an inflection point occurring at a scale operation level of 27.15, and this result remains robust after a series of tests; (2) Moderating effect analysis shows that an increase in hired labor for corn production significantly strengthens the inhibitory effect of large scale operation of agricultural land on corn yield, while improvements in corn mechanization rate and agricultural socialized services do not exhibit statistically significant moderating effects on the scale-yield relationship. Therefore, to coordinate large scale operation of agricultural land with grain security, it is necessary to move away from a scale-oriented approach and establish a dynamic, tiered support system, strengthen the foundational support of mechanization and socialized services, and address the cost challenges of field management through specialized services and intelligent equipment.