Implementing green Information Technology (IT) is an effective way to realize sustainability. In the process of implementing green IT, IT transformation is essential but tends to fail. However, existing literature can't offer effective guidance for implementing green IT. In this article, we conduct a case study of green IT implementation at Shenyang Aircraft Corporation, an aircraft manufacturer. This study sheds light on the process through which green IT transformation and sustainability are achieved. Consequently, we have expanded the Belief-Action-Outcome (BAO) framework to strategic and operational levels, and summed up the capabilities and mechanisms of each phase, as well as the impact relationships and directions between each phase. At a strategic level, the belief formation phase includes the capability to establish direction and required actions, containing formation of belief in sustainability and cultivation of green culture. The action formation phase needs the capability to reshape strategy and required actions, containing green informatization strategy and the establishment of a green IT group. As for operational level, the belief formation phase needs the capability to integrate and engender trust, the combination of production and research as well as production network implementation constitutes required actions. The action formation phase includes the capability to enact a sustainable plan and required actions have two parts: paperless production and a balanced production plan. This study contributes to present literature from three aspects. First, the study provides a qualitatively empirically grounded framework for the study of green IT. Second, this study contributes to the literature on sustainability from an IT perspective. Finally, our study also made important contributions to the BAO framework.