Against the backdrop of intensifying global urgency in climate governance and the deepening advancement of China's "Dual Carbon" goals, the clarification of influencing factors of new quality productive forces on carbon efficiency is crucial for urban green transformation. A measurement system for new quality productive forces was constructed, encompassing six dimensions: data factors, new-type workers, new-type means of labor, technology research and development, new production organization, and new-type objects of labor. The non-radial directional distance function was employed to measure carbon efficiency at the prefecture-level city level, which is further decomposed into efficiency change and technological change. Furthermore, by integrating the LightGBM model with SHAP methods, the association characteristics between each element and carbon efficiency were systematically identified. The results indicate that data factors, new-type workers, and new-type means of labor serve as core driving forces for improving carbon efficiency, whereas technology research and development, new production organization, and new-type objects of labor exhibit potential influences. Regarding nonlinear relationships, most elements demonstrate threshold effects. Specifically, data factors and new-type means of labor display a U-shaped influence structure. The effects of new-type workers and new-type objects of labor show significant maturity dependence and scale threshold characteristics, while new production organization presents a phased positive impact. Mechanism decomposition reveals that efficiency change is primarily driven by the optimization of resource allocation by data factors and new production organization, whereas technological change is more supported by frontier technological innovations in new-type means of labor and new-type objects of labor. The green effect patterns of new quality productive forces are identified, providing a reference for precise urban low-carbon policy-making.