Abstract: In recent 40 years, the developing rate of desertification is 0.81%-1.64% per year in the north of China.The researchers emphasize particularly climate and man-made factors of present time, but over look the effect of environmental evolution on the study of desertification.The authors analyze evolution process of climate, sand blown by wind, loess and environment of Quaternary since 20000 years, and have the study of quantitative and contrast, using GIS on desertification of three periods of time including dry-cold, warm-humid and dry-cold.The result indicates that the important factor to make drought and desertification in north is the uplifting of Qinghai-Xizang Plateau in 10 000 years.The time scale on which natural factors cause desertification is ten thousand years or thousand years, while that of human efforts is only hundred years or decade.Quaternary environment is the foundation of desertification formation and the desertification of vegetation and soil covering is direct cause leading to the present desertifacation.In recent 50 years, climate in the north of China evolves to dry and heat.Thus, desertification protection is an important task for China in the 21st century.