The intergovernmental collaborative governance of regional environment is the proper choice to deal with regional environmental problems. For this reason, it is necessary to reveal the collaborative realization mechanism of intergovernmental cooperative governance of regional environment. On the analysis of the practical problems of joint prevention and control of air pollution in BeijingTianjinHebei region, using the principle of order parameter in synergetic theory, this paper identifies the order parameters of the intergovernmental collaborative governance of regional environment including the concept of a community with a shared future, incentive compatible crossinterests, perfect and efficient institutional arrangements and adequate information sharing, which constitute the concept guidance mechanism, interest incentive mechanism, system guarantee mechanism and information entropy reduction mechanism. In order to realize the effective governance of the regional environment in the future, we should actively incubate and cultivate the order parameters, including shaping a common vision, strengthening multicompensation, perfecting rules and procedures, and breaking down information barriers.