Abstract: Accelerating county-level new urbanization is an effective means of promoting economic development and achieving common prosperity. New quality productive forces provide strong momentum for its high-quality development. Based on 52 cases of county-level new urbanization across China and grounded in synergy theory, this study employs fuzzy-set qualitative comparative analysis (fsQCA) to explore the configuration paths leading to high-quality development from the perspective of new quality productive forces across five dimensions: technological productivity, digital productivity, green productivity, industrial productivity, and inclusive productivity. The results reveal that the high-quality development of county-level new urbanization is jointly driven by the synergistic effects of these dimensions. Four configuration paths are identified and can be categorized into three types: industry-driven, technology–inclusiveness synergistic, and all-factor synergistic. Among these, technological productivity serves as the core element, playing a crucial role throughout the process. The findings enhance understanding of the multi-factor combination mechanisms underlying high-quality county-level urbanization from the perspective of new quality productive forces. They also offer practical insights, suggesting that local governments should strengthen the interaction among various dimensions of new productive forces, fully stimulate technological innovation, and select configuration paths suited to local conditions.