It is impossible to use traditional techniques to study water resources carrying capacity in a data-deficiency region where water resources have been over loaded severely.This study takes the groundwater carrying capacity of Barun irrigated district in oasis of 2010 and 2015 in Alashan,Inner Mongolia Autonomous Region as an object of investigation.Based on the analyses of the limited data,with the help of a nonlinear regression analysis method,a new evaluation criterion was presented and an analytic model of groundwater carrying capacity was built according to the law of water supply and demand balance.A method of Lagrange multiplier rule was applied to solve the analytic model.Results demonstrate that the analytic model has the ability of analyzing and evaluating the groundwater carrying capacity for data-deficiency region where excessive exploitation of water resources has taken place.The results can offer new references for similar researches on water resources carrying capacity in other data-deficiency regions.