The causes of the disappearance of the ancient town of Loulan in Xinjiang,China have been generally agreed to derive from two factors: human activities and natural factors(environmental variations).In this paper,the Muzart Glacier was selected as an example,and found that the length of the glacier has been gradually decreasing and the snow line has been retreating to a higher altitude,both results contributing to a decrease in river flow below the Muzart Glacier.From the distribution of moraines in the Tianshan Mountains and adjacent areas in different periods,the paper speculates that there have been four minor glacial periods since the Quaternary.Although the durations and scales of the four minor glacial periods were different,they all indirectly influenced the formation and disappearance of the Lop Nur Lake.The events of the fourth minor glacial period are the important impact factors in the existence and disappearance of Loulan.Whether the disappearance of Loulan can be related to the events of the three previous minor glacial periods needs further investigation.