Rural revitalisation is the sole path to national rejuvenation, and the rural economy is the key and complex factor of rural revitalisation. High-quality development of rural finance is the benign driver of rural economic development and revitalisation. This study defines the connotation of high-quality development of rural finance. As a product of "quantitative expansion" at a certain stage, rural finance should include the dual dimensions of "quantity" and "quality", and their symbiosis and coordination determine the realisation of system functions. Considering "quantitative expansion" and "qualitative improvement" as the framework, the study determines "coverage breadth", "coverage depth", "institutional sustainability" and "developmental sustainability" as sub-indicators to build an evaluation index system including 13 basic indices. This study adopts the entropy weight method to synthesise and measure indices of "expansion of quantity", "improvement of quality" and the overall index of "quantity-quality combination" from 2009 to 2018 to analyze the spatiotemporal differentiation characteristics of the level of high-quality development of rural finance. This study results reveal that in terms of spatial differentiation performance, the level of high-quality development of rural finance in China is generally increasing, and the improvement in the overall level in the Western region is more significant. Concurrently, there is a gradually decreasing difference between the observed values of "quantity expansion" and "quantity-quality combination", whereas the difference in the "quality improvement" index is slowly expanding. There is an evolutionary process of "negative correlation → positive correlation → low correlation" in the relationship between "quantity expansion" and "quality improvement", especially the gradually decreased synergy in recent years, indicating that "quality improvement" is not mainly constrained by "quantity expansion". In terms of differentiation performance of spatial dimensions, robust spatial differences exist in the levels of "quantity expansion" and "quantity-quality combination". The overall distribution characteristics are consistent with the national economic development level, forming a gradient differentiation pattern that increases layer-by-layer from west to east, with the Heihe-Tengchong Line as the main boundary. This differentiation pattern has neighbour diffusion, revealing a "westward" trend. The overall "quality improvement" in rural finance is still low. From 2015 to 2018, the level of "quality improvement" started showing a highly differential pattern. Provinces with higher levels of differentiation are distributed in different economic regions. This differentiation pattern has leap diffusion and shows a "northward" trend. Overall, "quantity expansion" and "quantity-quality combination" characterised by neighbour diffusion drive the local spatial agglomeration connection in spatial differentiation, whereas "qualitative improvement" characterised by leap diffusion in spatial differentiation promotes the local spatial dispersion connection. According to the study results, this study proposes the following findings:based on fiscal and tax policies, ensure the complete development of the rural financial market and promote financial organisations to disengage from the behaviour of "elite capture"; improve the availability of financial services in the field of "agriculture, rural areas and farmers" by reducing transaction costs, expanding service boundaries, improving the skills of financial institutions and increasing information transparency; and strengthen the capacity-building of businesses and development sustainability of rural financial institutions.