Abstract: Agricultural science and technology innovation is a core driver of high-quality development of the rice industry. Using panel data of 65 prefecture-level cities in the middle and lower reaches of the Yangtze River for the period 2010 to 2023, this paper employs two-way fixed effects, mediation-effect, and threshold-effect models to examine its impact and underlying mechanisms. Results show that: 1) agricultural science and technology innovation significantly promotes the high-quality development of the rice industry, and this finding remains robust after instrumental variable estimation, Tobit regression, and winsorization tests; 2) mechanism analysis indicates that it indirectly promotes industrial upgrading, while the mediating effect of structural rationalization is insignificant; 3) heterogeneity analysis reveals that the driving effect is more pronounced in regions with stronger supporting capacity, higher economic development, and plain terrain; and 4) threshold analysis identifies a single threshold effect, with the positive impact becoming significantly stronger once the threshold is exceeded. Based on these findings, this paper suggests strengthening foundational support, promoting value chain upgrading, and implementing differentiated strategies to fully unlock the potential of agricultural science and technology innovation to drive the high-quality development of the rice industry.