Taking the climate of the Last Glacial Maximum (about 26000 years ago to 19000 years ago) as the background climate, the authors study the climatic impact of the expansion of the glacier on the Tibetan Plateau using the atmospheric general circulation model CAM4 coupled to the land surface model CLM4. The results show that in summer the increased glacier extent over Qinghai-Tibet Plateau has a significant impact on the climate in the Northern Hemisphere. Besides the significant temperature decrease on the glacier, atmospheric teleconnection can also cause significant warming near the Bering Strait. In addition, the disturbance caused by glaciers will enhance the South Asian summer monsoon and increase the precipitation there. Finally, through comparing the influence of the scale of the Qinghai-Tibetan glaciers on the climate under the different climate states of the Last Glacial Maximum (LGM) and Pre-industrial (PI) periods, it was found that their influence in the PI period was significantly less than that in the LGM period. It indicates that impact of Tibetan glaciers on climate is related with the climate state.