Building a strong nation requires strong agriculture. Developing agricultural new quality productive forces (ANQPFs) is the key to achieving a leap from a major agricultural country to an agricultural powerhouse. The financial difficulties and hidden loss of benefits in agricultural counties have weakened the enthusiasm of local governments to develop agriculture, which is a key factor restricting the development of ANQPFs. As a typical targeted incentive mechanism, the Granary County Subsidy Program, through fiscal transfer payments, still needs to be systematically tested for its capability to alleviate local financial pressure and promote the development of ANQPFs. This paper constructs a Bunching-DID model and uses the policy entry threshold as an institutional breakpoint to identify the impact of the Granary County Subsidy Program on the ANQPFs in strategic grain-producing counties and typical grain-producing counties. The results show that: First, the policy effectively enhances the willingness of county-level governments to develop agriculture, forming a significant bunching phenomenon on the right side of the policy entry threshold. Second, the policy significantly stimulates the development of ANQPFs in strategic grain-producing counties, and this effect is mainly achieved through expanding agricultural socialized services and optimizing resource allocation. Third, the incentive effect of the policy on the ANQPFs in strategic grain-producing counties varies with fiscal conditions and industrial endowments, revealing a mismatch between willingness and effectiveness. This paper helps clarify the willingness and funding allocation orientation of local governments in responding to agricultural fiscal transfer payments, offering micro evidence for the central government to further improve agricultural targeted incentive mechanisms and strengthen the endogenous driving force of ANQPFs.