The Mid- Pleistocene transition (MPT) is an important period of Quaternary environmental change, during which climatic patterns and cycles changed significantly. However, the response characteristics of different regions to the Mid- Pleistocene transition were significantly different. In this study, 207 samples were selected from the XZK4 core in the Changzhi basin before and after the Mid- Pleistocene transition. By means of paleomagnetic dating, grain- size, End- Member and pollen analysis, the characteristics of environmental changes and lake evolution during the Mid- Pleistocene transition period in the Changzhi basin were reconstructed. The results showed that since 1. 8 Ma (i) the content of tree pollen in the pollen assemblage was more than 60%; (ii) some periods were dominated by herbs pollen indicating that most stages of regional vegetation were forests, but there were obvious cold periods; and (iii) the interval 1. 1 Ma and 0. 55 Ma was an important turning point of environmental transformation in the study area. Before the Mid- Pleistocene transition (~1. 1 Ma), the overall grain- size of the sediments was relatively fine, the clay content was more than 25%, the EM1 component (representing lacustrine components) was more than 60%, and the EM3 component (representing fluvial facies component) appeared in some periods. The overall results showed that the sediments in this stage were mainly lacustrine components, and some stages were greatly affected by rivers. However, during the Mid- Pleistocene transition (1. 1~0. 55 Ma), sediment grain- size were finer with average 30% clay content, sediment color was predominantly gray- brown, and pollen concentrations and EM1 component achieved the highest values, while EM3 component was at its lowest, during 1. 1~0. 95 Ma, Picea pollen shows that the study area was generally cold and wet, and the lake area expanded. After the Mid- Pleistocene transition (~0. 55 Ma), sediment grain- size was significantly coarser, sediment color was predominantly yellow, EM2 (indicating eolian component) and EM3 are dominant, herbs content increased, especially dry Artemisia pollen significantly increased. All these indicate that the climate is drier after the Mid- Pleistocene transition, with increased eolian sediments and disappearance of the lake. A comprehensive comparison shows that tectonic movement is the main driving force affecting the rise and fall of the paleolake in Changzhi, and the climate drying exacerbated the disappearance of the lake.