The complexity of hydrological process in frozen regions makes its analysis and simulation difficult. When researching on hydrological impacts of frozen soil degeneration in Tibetan Plateau,it is needed to know spatial and temporal distribution characteristics of soil freezing and thawing status. Making use of surface soil freeze / thaw status derived from passive microwave remote sensing data,spatial and temporal distribution and variation characteristics of surface soil freezing and thawing status in the Upper and Middle Nujiang River Basin was identified. The results showed that: (1) In much of Nujiang River Basin above Gongshan station,the area with more than 270 surface freezing days covered 32.0% of total area,and the area with surface freezing days between 180 and 270 days accounted for 62.3%. On average,annual surface freezing days were increased by about 62 days with every 1000 m elevation. (2) The start and end time of continuous freezing status in the study area varied in different years. The correlation coefficient between average temperature in thaw-freeze stage (September to October) and freezing area in October was - 0.80,while the correlation coefficient between average temperature in freeze-thaw stage (April to June) and freezing area in June was - 0.87. Both reach 0.01 significant level. Interannual fluctuation of air temperature resulted in the variations of surface soil freezing area and duration,and the start date of freezing and thawing status. (3) Surface soil freeze /thaw status derived from passive microwave remote sensing data,with high time resolution,could be applied in large-scale freeze /thaw variations analysis and hydrological simulation under climate change,especially in ungauged plateau and mountain watersheds.