Xintiangou Formation is a key stratigraphic interval beneath the wide- spread Jurassic red strata in the Sichuan basin, and records the climatic change from humidity to drought in the early Middle Jurassic. However, previous researches focused mainly on palaeoclimate patterns, and lack of deep and systematic study of climatic change. This paper investigated geochemical characteristic of mudstone from the Taba section of the Middle Jurassic Xintiangou Formation. The results show that seven climatic proxies (CIA, C- value, Sr/Cu, Sr/Ba, Rb/Ti, Cs/Ti, Rb/K) are indicative of the palaeoclimate change from hot and humid to drought, and dominantly semi- arid- semi- humid climate. However, the process of the climate change was not stable, fluctuating in several hot/humid and dry periods. At the end of the Xintiangou Formation sedimentary period, climate condition became extremely dry. The geochemical characteristics of the Xintiangou Formation mudstones in the northeastern Sichuan Basin records the climate changes at a crucial turning point of geological history, indicating that the climate started to respond before occurrence of large- scale deposition of Jurassic red bed. During the early Middle Jurassic, the Sichuan basin was no in the same climate zone as the Europe.