Abstract: Urbanization is the inevitable path to modernization, and promoting county-level urbanization is a crucial choice for realizing China's modernization. Mountainous counties, as the primary type of county units in China, accelerating their urbanization development holds great significance for implementing national functional zoning strategies, advancing the new urbanization strategy, fostering coordinated regional and urban-rural development, and comprehensively promoting common prosperity. Currently, the level of county-level urbanization in mountainous counties still lags behind that of counties and cities where urbanization occurred earlier. Thus, it is imperative to expedite the exploration of high-quality county-level urbanization paths and patterns in mountainous counties. This paper takes Xianju County, Zhejiang Province, as the research object. Based on an analysis of the advantages of county-level urbanization in this county, it is proposed that Xianju County can promote countylevel urbanization by adopting five paths: improving the county layout, strengthening the county's industrial base, enhancing public services, elevating the quality of facilities and buildings, and fostering population agglomeration. Furthermore, a 'trinity' model is been formulated, centered on comprehensively enhancing the county's capabilities, with a focus on significant population agglomeration and supported by substantial brand promotion. This serves as a valuable reference for other mountainous counties nationwide that aim to promote county-level urbanization. In conclusion, the research findings indicate that mountainous counties must prioritize industrial development in their pursuit of county-level urbanization, consistently enhance the county's capacity to provide high-quality public services and infrastructure, and safeguard and develop the county's unique historical, cultural, and ecological resources.