Water resources are seriously lacking in the low mountainous area of Northeast Sichuan where mesa(table mountain) is a topographic character. With the mesa in Qiankouling, Dazhou, Sichuan Province as the research object, we expounded the causes of water shortage from aspects of geology,geomorphology,climate,land use,and water conservancy, and further discussed the measures of water conservation and evaluated the comprehensive benefits of the measures. Results show that mesas in the study area are prone to suffer from water shortage due to the strata of Qiankouling mainly composed of thick or mega-thick sandstone, the tectonic fissures and weathering fissures, as well as the geomorphic characteristics of “flat top, steep slope, and gentle foothills”. Controlled by the subtropical monsoon and the subtropical high, the spatial and temporal distribution of precipitation is uneven, easily leading to summer drought and spring drought. Moreover, the land use, farming system and historical reasons of water conservancy facilities make the crops insufficiently irrigated. Three small-scale water conservancy engineering measures suitable for the Ω-shaped trough valley, the saddle (narrow pass between two trough valleys), and the gentle terrain in mesa region are put forward to provide reference for solving the problem of water shortage in similar areas.