Index including water level, water depth and area was employed to quasi-quantiflcationally study the spatial change of lake water quantity in the east and west regions of China during the past 50 years. The results indicated that, as a whole, lake water quantity showed a wave change in the east regions of China while a decrease tendency in the west before 1980s. Since 1980s, it showed an increase tendency at different degree in the east and west regions. In 1950s, high lake water quantity occurred both in the east and the west regions of China. Water quantity in the east regions showed a little decrease in 1960s, while lakes in the west regions displayed a middle-high status. In 1970s, there was a steady-going medium lake water quantity occurred in different regions of China. Lake water quantity in the east regions showed an increase tendency in 1980s, while in the west a little decrease compared with that in 1970s. In 1990s, an increase tendency occurred both in the east and west regions of China. Further studies revealed that not only climate incurred the changes of lake water quantity, but also human activities showed important effect.