Abstract: The improvement of new quality productivity in agriculture is an important way to achieve modernization in rural areas and agriculture. As an important means of investment in new quality productivity in agriculture, fiscal support for agriculture shoulders significant responsibilities in the agricultural sector. Based on the panel data of 30 provincial administrative regions in China (excluding Xizang, Hong Kong, Macao and Taiwan) from 2013 to 2023, this paper measured the level of new quality productivity in agriculture and the level of agricultural industrial integration by constructing an index system, and analyzed the impact and mechanism of fiscal support for agriculture on new quality productivity in agriculture by using the two-way fixed effect model and the mediation effect model. The results showed that: (1) Fiscal support for agriculture could not only significantly promote the development of new quality productivity in agriculture, but also indirectly promoted the development of new quality productivity in agriculture by improving agricultural industrial integration and reducing agricultural carbon emissions. (2) Heterogeneity analysis showed that, compared with other regions, fiscal support for agriculture had a significant promoting effect on new quality productivity in agriculture in flat areas, steep areas, major grain-consuming areas, and regions with low levels of fiscal support for agriculture. Therefore, it is suggested that through further optimizing the structure of fiscal expenditure, improving fiscal support policies for agriculture, and adjusting agricultural production models, etc., decision-making references can be provided for achieving modernization and high-quality development in rural areas and agriculture.