In order to explore the response of snow cover to climate conditions under the complex topography， based on composite snow cover products on eight days of MOD10A2，daily temperature and precipitation from September 2001 to August 2020 and digital elevation model（DEM）in the Yellow-River source region，the snow cover frequency and percentage was used as an index to study the spatio-temporal variation characteristic of snow cover and their relations with major meteorological elements. The results are as follows：（1）Snow was mainly appeared from October to next May in the Yellow-River resource region，and the higher altitude，the greater snow cover percentage and the longer duration. Snow mainly distributed in high mountainous areas. The yearly accumulative process of snow showed a U-shaped at the altitude of 3500 m and below，the peak appeared in win‐ ter，while that transited to inverted W-shaped above the altitude of 3500 m，and the gap between two peaks grad‐ ually reduced with the rising of altitude，the appearing time of the maximum peak shifted from spring to autumn. （2）The snow cover percentages on the northern and northerly slopes were more than that on the southern and southerly slopes during the accumulative period，among the maximum was on the northeastern slope，and the minimum was on the southern slope，but the yearly variation characteristics with inverted W-shaped were similar and synchronous on each slope，the maximum and secondary peaks appeared at the end of October and the early of April，respectively.（3）Under the background of warming and humidification，the snow cover percentage dur‐ ing the accumulative period exhibited an overall increasing trend with a rate of about 5. 6% per 10-year in the Yel‐ low-River resource since 2001，especially at heights above 4000 m. The significant increase of snow cover area in spring and winter at heights 4000~5000 m contributed greatly to the increase of snow cover percentage during the accumulative period.（4）The average snow cover percentage first increased and then decreased with the de‐ cline of temperature and the increase of precipitation during the cumulative period in each altitude zone of the Yellow-River source，and the higher the altitude，the higher the fitting goodness between the two. The consistent increase of precipitation was the key factor contributing to the increase of snow cover percentage in each season of accumulative period since 2001，especially the significant increase of precipitation at high altitude areas in spring. Snow was more dependent on precipitation at high altitude areas.