This paper explored the feasibility of using water level data from a single short-time satellite source to estimate long-term changes in lake water volumes. Combined with Sentinel-3A synthetic aperture radar altimeter (SRAL) in 2016-2018 and lake water areas extracted from Landsat satellites during 1988-2018, the relationship between water level change and water area change in non-glacial period of 2016-2018 and the water volume estimation formula were used to analysis the inter-annual changes of water level and water volume from 1988 to 2018, the intra-annual change from 2001 to 2018 and the main causes of such changes. Results show that lake area, water level and water volume of Tangra Yumco rose significantly in the past three decades, increased respectively by 21.1 km², 5.29 m and 4.47 billion m³ from 1988 to 2018. Although declines in the lake area and water level and water volume decreased during 1988-1998, the lake expanded during 2000-2018, exhibiting the characteristics of the dry and wet seasons during the period of 2001-2018. From 1996 to 2014/2015, the lake water volume change was from 3.83 billion to 3.55 billion m³. Such water volume changes are in good agreement with previous research. Lake expansion occurs in the southeastern and mid-western regions where the underground-water terrain is gentle. Based on the data from global land surface data assimilation system (GLDAS) and glacier snow lines, both the changes in precipitation and air temperature exhibited strong correlations (with R² of 0.613 and 0.845, respectively) with the changes of water volume over the period 2008-2018. The wet season of lakes was significantly affected by precipitation and air temperature. This study shows the potential of sentinel-3A SYNTHETIC aperture radar data in the estimation of lake water quantity change, and provides a basis for the estimation of lake water quantity change in a long time series by using a single satellite radar data with only short-term data.