<p>With the growing emphasis on sustainable development, government green procurement (GGP) has become a critical tool to drive green transformation in manufacturing industries. The study aims to examines the selection of an appropriate order allocation mechanism for distributing green product orders in GGP from manufacturing enterprises. First, based on the Stackelberg game model, three order allocation mechanisms are used to explore the product greenness and bidding price of manufacturing enterprises. Moreover, the incentive effects of GGP are compared to explore the optimal order allocation mechanism. Finally, numerical simulation is conducted to analyze the relationship between product greenness, the bidding price of manufacturing enterprises, and green productivity under the three auction models. The results show that (1) The FPA and SPA yield similar incentives when all orders are awarded to one firm. (2) The FPA is more effective in supporting low-cost green procurement compared to SPA and OSA. (3) The GGP price rises in response to growing variations in green productivity across manufacturing enterprises. These findings suggest that FPA is preferable for cost-sensitive procurement, while OSA is better suited for encouraging green innovation. Policymakers are advised to implement a dynamic mechanism that shifts from SPA to OSA as green productivity differences grow, thereby enhancing the efficiency and impact of green procurement.</p>