The Logic of Collaborative Strategy Selection for Regional Environmental Sustainability: An Empirical Study of Intergovernmental Relations in the Beijing–Tianjin–Hebei Region

Effective intergovernmental collaboration is essential for regional environmental sustainability. Using the Beijing–Tianjin–Hebei (BTH) region as a case study, this research examines how different collaborative relationships influence governance behaviors and outcomes. By classifying collaborations into formal and informal types, we employ a Probit model to analyze their intrinsic dynamics. The key findings are as follows: (1) Under different types of intergovernmental collaborative relationships, governments adopt distinct collaborative governance behaviors. The Probit estimates indicate that under hierarchical pressures, Multi-level relations significantly increase the likelihood of formal tools (β = 1.010, p < 0.05), whereas Diagonal ties strictly favor flexible informal mechanisms (β = −1.116, p < 0.01). (2) Cumulative cooperation experience reduces transaction costs, driving a profound shift toward informality at the 1% significance level across all baseline models. (3) When addressing collaborative governance matters that require cross-provincial cooperation, governments tend to adopt formal collaborative behavior models. (4) When facing urgent environmental issues that demand rapid resource mobilization and immediate decision-making, collaborative governance participants prefer informal collaborative governance approaches. This study clarifies the behavioral logic of local policy tools, offering an institutional framework to optimize regional collaborative networks and advance long-term environmental sustainability in complex eco-corridors.