Drawing upon the integrated theoretical framework of Systemic Functional Linguistics and Fairclough’s three-dimensional discourse analysis model, the article uses corpus-linguistic methods to investigate the ecological image constructed in major Chinese oil and gas companies’ sustainability reports (2012–2023) through the representation of climate change. It analyses the frequencies and the collocations of the terms ‘climate change’, ‘global warming’, and ‘climate-related risks’. The findings show that the ecological image of Chinese oil and gas companies is characterized by their growing concern over climate change. Initially, these companies regarded climate change as a challenge, but recently they prefer to represent it as an opportunity for development. They acknowledge the crises caused by climate change while emphasizing its global significance. The companies focus on the measures to manage climate change and its related risks. Moreover, they highlight the significance of energy efficiency and transition, ecological protection, and emission reduction in the context of climate change. Finally, it can be argued that the ecological image of these oil and gas companies is influenced by various sociocultural factors, including international and domestic climate policies, corporate strategic measures, and GRI disclosure standards.