Abstract: In the investigation of groundwater pollution of regional scale and limited sample, sampling point distribution should according to the difference of geological environment and human activities et., although the density control can calculate the total number of samples.At present, the issue of uncertainty exist in sample distribution, because it mainly based on the experience of technicians. Scientific choice sampling point is a scientific problem we need to solve.A solution is proposed to solove this problem，based on practical work.The solution mainly contains two aspects:regional pre-distribution and unit re-optimization. A pre-distribution method is based on analytic hierarchy process (AHP) and a unit re-optimization method depend on hydrogeological condition.The distribution factor combination of the background and pollution potential aspects is proposed, and the scaling method of qualitative and quantitative factors are recommended. Taking the Lhasa river basin groundwater quality survey as an example, the solution is used to calculate and allocation samples in region and choose samples in each unit. The results show the hierarchical analysis model and quantification method can satisfy the actual needs of each unit in Lhasa River Basin, such as the contradiction of area and population between Chengguan district and Dangxiong county. Segmental control and condition optimization provide basis for the selection of sampling points. This study provide a method for sample quantitative distribution in regional groundwater pollution investigation.