CO₂ emission which has a big impact on environment has caught global attentions. Air pollution and greenhouse effect are jeopardizing human being's environment. In 2009, the world economy steps into a downturn, but the climate change is still a core question for petroleum companies to concern, who are considering to carry out an environment-friendly policy to boost the economy. Using the abandoned oil reservoirs to bury CO₂ is regarded to be effective, which had been studied for a long time. This paper, based on a successful case of Dazhangtuo gas reservoir, analyzes the geology and economic advantages of using abandoned oil reservoirs in China, discusses how to choose the sites to bury CO₂, and presents some suggestions, hoping to provide theoretical and practical references for sustainable development and highlevel development of resources and environment.