The Sichuan Basin is one of the most representative basins in Cretaceous terrestrial basin, in which a suite of red clastic deposition, especially gypsum and desert facies had been widely deposited. Based on previous study, climate marker of clay minerals, composition of the rocks, this study discusses climate and its evolution of the Sichuan Basin and adjacent areas in the Middle Jurassic to the Early Paleogene. Our experimental results suggest that the Early Cretaceous tectonic factors played a dominate role in the northern margin of the Basin, whereas the south was predominated by weather, suggesting that tectonic activity had little effect on sedimentation. The main clay minerals in the redbeds are illite and smectite. Both Illite and smectite are present in most samples, implying that climate of the source area was cool and arid. Illite present locally stands for a cool, dry clmite. Chemical index of the illite samples is higher than 0.5, indicating that clay minerals had undergone strong chemical weathering and interior of the Basin had a relatively warm and wet climate.