As an institutional innovation that advances fiscal and financial coordination and facilitates the effective synergy between the government and the market, policy-based agricultural credit guarantee plays a vital role in alleviating the “difficulty and high cost of financing” for agricultural business entities, accelerating agricultural and rural modernization, and promoting rural revitalization across the board.By elaborating the theoretical connotation of the high-quality development of policy-based agricultural credit guarantee, this paper constructs a comprehensive evaluation index system from perspectives of quantitative growth and quality improvement.Based on the panel data of 29 provincial institutions in China from 2018 to 2023, it systematically investigates the level characteristics, spatiotemporal evolution patterns, and key obstacle factors of its high-quality development by comprehensively using the entropy weight method, kernel density estimation, Moran’s I index, Markov chains, and obstacle factor diagnosis model.The results show that the overall high-quality development level of policy-based agricultural credit guarantee in China is relatively low, with a prominent imbalance between quantitative growth and quality improvement, leaving substantial room for quality improvement and efficiency gains.Spatiotemporal evolution analysis indicates that the development level has been rising steadily while regional disparities continue to widen, forming a significant positive spatial agglomeration pattern.The level transition of development features both strong path dependence and asymmetric spatial spillover effects.This evolution trend not only directly reflects regional disparities in agricultural industrial endowments, fiscal support capacity, and market-oriented operation level, but also mirrors spatial transmission effects such as regional industrial chain linkages and mutual learning and sharing of policy experience.Further analysis reveals that recovery rate, contribution to agriculture, contribution to the agriculture-related credit market, average number of employees per county, and average outstanding guarantee balance per county are the major obstacle factors.These bottlenecks concentrate in three core links (i.e., risk disposal, industrial adaptation, and county-level services) and serve as the deep-seated causes of widening interprovincial gaps and low-level development lock-in.Accordingly, targeted measures should be taken from four aspects: optimizing performance evaluation orientation, consolidating county-level service systems, deepening business model innovation, and strengthening regional coordination.These efforts will drive the transformation of policy-based agricultural credit guarantee from scale expansion to coordinated advancement of quantity and quality, and fully unlock its institutional effectiveness for agricultural support.