Green logistics policies (GLP) are essential to the progress of green logistics, the promotion of green growth, and the fulfillment of sustainable development. However, as the uncertainty and ambiguity of factors that influence the implementation of GLP, it is urgent to explore and reveal the antecedents and functional mechanism of the effectiveness of GLP. This study adopts grounded theory method to conduct in-depth interviews, and concludes that five major factors, such as the perfection of GLP system, the green governance capacity of government, the level of perception of logistics enterprises on GLP, the level of social supervision, and the development level of logistics industry, which influence the effectiveness of GLP. And then presents the integrated model of antecedents of the effectiveness of GLP, revealing the influence path and internal mechanism of these influencing factors. It is of great significance to enhancing the effectiveness of GLP, upgrading green logistics, and achieving the green development.