Abstract: As a new goal and requirement for China's agricultural development, the development of agricultural new quality productivity carries profound implications for rice yield, which is intrinsically linked to national food security. While existing research mainly explored the relationships between the development of agricultural new quality productivity and grain production from a theoretical standpoint, this study further systematically investigates the influence of agricultural new quality productivity on total rice yield and the underlying mechanisms from both theoretical and empirical perspectives. Importantly, it also considers the heterogeneous effects of agricultural new quality productivity across different scales of rice production and diverse geographical regions. For these purposes, based on provincial panel data from 2012 to 2023, a comprehensive evaluation index system for agricultural new quality productivity was established from three key dimensions: agricultural laborers, agricultural labor objects, and agricultural labor materials. Then, the study employs the fixed effect model, the mediating effect model, the threshold model, and the spatial econometric model to rigorously test the proposed relationships. The empirical findings yield several critical insights. First, agricultural new quality productivity exhibits a significant negative impact on total rice yield. This result remains robust after accounting for potential endogeneity and conducting a series of robustness tests, including winsorization of extreme values, an alternative dimensionality reduction method for the index of agricultural new quality productivity, and exclusion of selected subsamples. Second, the mechanism analysis shows that agricultural new quality productivity has an adverse effect on rice cultivation area though it increases the yield per unit area. The magnitude of this area-reducing effect substantially outweighs the productivity gain per unit, leading to an overall decline in total rice yield. Third, threshold regression results indicate that the relationships between agricultural new quality productivity and both total rice yield and yield per unit are nonlinear and contingent on the scale of rice planting area. Specifically, when the rice planting area exceeds threshold values of 3.3810 and 2.8214 (in standardized units), the effects of agricultural new quality productivity on total rice yield and per unit yield shift from negative to positive, respectively. Besides, regional heterogeneity analysis highlights distinct spatial patterns. Agricultural new quality productivity significantly reduces total rice yield in central China, while it increases total rice yield in the western region significantly. Similarly, it significantly boosts total rice yield in major rice producing zones, while it has an opposite effect in non-major rice producing zones. Last, the negative influence of agricultural new quality productivity on total rice yield exhibits spatial spillover effects, which means it not only reduces the total rice yield in the local region but also negatively affects the yield in neighboring areas. In light of these findings, agricultural new quality productivity may conflict with the goal of total yield stabilization in key staple crops such as rice. Therefore, to harmonize agricultural new quality productivity advancement with total rice yield assurance, it is imperative to implement integrated measures that fully safeguard rice cultivation area, optimize the regional development layout, and improve the scale level of rice production.