The major advances in the researches on the variability of snow cover over the Qinghai-Tibetan Plateau (QTP) and its impact on water resources in China are summarized. Some existing problems in the related studies and the researches needing further investigation are also discussed. The distribution of the snow cover over the QTP is far from uniformity. In the peripheral high mountains snow cover distributes extensively and has a long duration, but in the vast interior it is rare or even thin. The snow cover region in the east of QTP is the most significant region of the interannual variation of snow cover on the QTP, and dominates the interannual variation of snow cover in the whole plateau. So the snow anomalies over the eastern QTP should be paid more attention. The snow cover on the QTP increased from 1960s to 1990s, and its extent slowly increased in summer and autumn but decreased in winter and spring in the early 21st century. The research progresses on the impact of snow cover over the QTP on water resources are focused on precipitation and drought-flood. The abnormal snow cover over the QTP can affect the atmospheric circulation and Asian summer monsoon precipitation in terms of changing ground surface albedo, temperature and thermal conditions. The impact of abnormal snow cover over the QTP on precipitation is high consequence and wide areas. The abnormality of snow cover over the QTP has certain influences on droughts and floods of China. The snow cover abnormality could be applied in drought and flood forecast, too.