In order to better detect the high snow ablation law and its influence on runoff and the climate change , and study the relations between area, temperature and runoff,according to the MODIS snow product data of eight days from 2006to 2009, as well as the runoff and temperature data of hydrologic station at the same period, the paper analyzed the snow-melt runoff characteristics of KM river basin, the quantitative relations of snow area, temperature and snowmelt runoff. The results indicate that ablation of snow ends at 2000m above sea level in March; snow at 2000to 3500m above sea level began melting on March 10,the ablation is completed at the end period of snow ablation;,snow at elevation of 3500to 4500m starts thaw in early April, and has not completed the melt at the thaw end of the period; the change of snow area in snowmelt period is relatively stable at the elevation of equal or larger than 4500m. The area of snow and temperatures in every elevation zone of watershed has parabolic relation ,and the relevance become weak along with the rise of elevation.