Abstract: Based on the panel data of 285 prefecture-level cities from 2007 to 2020, the paper used stochastic frontier productivity model to measure agricultural total factor productivity, adopted two-way fixed effect model to analyze the effects of the scale and proportion of agricultural fiscal support on agricultural total factor productivity, and carried out mechanism tests based on the quantity and quality of agricultural factors. The results showed that the scale of agricultural fiscal support had a positive promoting effect on agricultural total factor productivity, while the proportion of agricultural fiscal support had a negative inhibiting effect. The way of fiscal promotion to agricultural total factor productivity is mainly achieved by reducing the quantity input of agricultural factors and improving the quality of agricultural factors. Therefore, we should strengthen the supervision of fiscal funds related to agriculture, establish a target management responsibility system, improve the performance of the use of fiscal funds related to agriculture, increase investment in funds for agricultural scientific and technological innovation, promote the popularization and application of agricultural scientific and technological achievements, improve the construction of financial support standards oriented by the quality of agricultural factors and promote agricultural powerhouse building.