The response of terrestrial vegetation during the end-Permian mass extinction remains a highly debated topic. We coupled the CESM Earth system model with the BIOME4 equilibrium vegetation model to recreate the dominant vegetation distribution and plant functional types around the Permian-Triassic Boundary (PTB)—the largest mass extinction event in Earth's history. Building on an existing 250 Ma equilibrium experiment and incorporating comprehensive quantitative assessments of global temperature changes, we designed experiments for before and after the PTB. Climate simulation results indicate that increased greenhouse gas concentrations led to global warming and the expansion of arid regions, directly contributing to the extinction of terrestrial plants. Vegetation feedbacks also affect the ocean.