Digital and intelligent policy instrument portfolio and green transformation of cities: evidence from China

In the digital-economy era, can policies represented by the national big data comprehensive pilot zones and the smart city pilot program work in tandem to effectively foster urban green development? Using panel data for 251 Chinese prefecture-level cities from 2006-2022 and a staggered DID model, this paper evaluates the multidimensional impacts of “digital-intelligent” policy collaboration on regional green transition. The findings are as follows: first, the dual-pilot policy significantly raises green total factor productivity in pilot cities, promotes local green transition, and generates marked green spatial spillovers; Second, the green co-empowerment effect of digital-intelligent policies is closely tied to regional characteristics and is further shaped by talent agglomeration and the strength of intellectual property protection; Third, mechanism analysis shows that the collaboration advances urban green development by improving energy consumption levels, enhancing digital technological innovation capacity, and strengthening industrial agglomeration; Fourth, heterogeneity analysis indicates that the empowering effect is more pronounced in regions with higher digital-economy development, stronger new-energy transitions, greater fiscal capacity, and service-oriented industrial structures; Fifth, further evidence shows that the empowering effect is strongest when green technological innovation surpasses a certain level and environmental regulation is of moderate intensity. In addition, compared with single pilots, dual pilots better promote urban green transition, and a sequencing strategy that implements “digital” before “intelligent” achieves superior outcomes. These results offer important guidance for local governments to coordinate multi-policy portfolios, harness synergistic policy effects, and accelerate economy-wide green transition.