Regional population shrinkage is becoming an important issue affecting the sustainable development of regional economy and society in the worldwide, and also arousing increasing attention in China. However, though some related studies in view of population distribution existed, few of them have directly addressed this phenomenon. Against this background, this article aims to investigate regional population shrinkage in China by employing multi-indicators. Specifically, we discussed the existing definitions of population shrinkage, and then based on the spatial population data of 1990, 2000 and 2010 in prefecture-level and county-level, applied both the single indicators, including total population and labor, and the integrated indicator which includes not only total population and labor but also birth rate and aging, to analyze the changes of population shrinking units in number and spatial distribution, and compared the differences in the measurement indicators. The main findings are as follows: 1) Both the single indicators, namely total population and labor, showed that population shrinkage units have increased significantly in number: 27.4% and 38.6% of the units decreased their total population while 21.4% and 25.2% of the units decreased their labor in prefecture-level and county-level from 2000 to 2010, respectively; moreover, many units also show an aggravation trend in the shrinking degree; 2) The population shrinking units have been expanding rapidly in the Central and the Western regions, especially in Sichuan-Chongqing- Guizhou region, the middle reaches of the Yangtze River region and the Northeast region. In contrast, the coastal region has only increased some shrinking units in the northern of Jiangsu Province and the western of Fujian Province; 3) The single indicators were effective in identifying the absolute population shrinkage, and we argued that the total population is more suitable than the labor, because total population shrinking came first in most of the units and then followed by labor shrinking; 4) The integrated indicator was more effective in evaluating the comprehensive status of population development in one region, and then it can identify the units which were relatively shrinking their population, that is, their overall situation is worse than the national average level though they still increased their total population. The results showed that the units with a relative shrinking population have a high proportion, which was about 20% in the county level in both periods, while that type of units in prefecture-level was nearly doubled to about 25% from 1990-2000 to 2000-2010. 5) Regional population shrinkage was more obvious in county-level than in prefecture-level, but the difference has been narrowed, given the fact that the differences in percentages, shrinking degrees, and spatial distributions of the shrinking units were very close in the period from 2000 to 2010. Based on the above findings, this article argues that regional population shrinkage needs further attention by scholars and governments.