With the case study on groundwater irrigation well investment in BaliYou Banner, Inner Mongolia, subproject of World Bank loan project, this article calculate the financial benefit for farmers to invest in such kind of activity by cash flow analysis approach. The calculation shows that the financial return of investment in groundwater irrigation well is quite high. So there is theatrical feasibility for farmers to invest in groundwater irrigation well solely or cooperatively. On base of the above calculation, this article also discusses the restrictive factors for farmers to carry out such kind of investment.