The main rock bed in Beiya Au orefield is the solution fissure karst aquifer. And the most ore bodies are below the local erosion basis 1 694 m (spring w123), which belongs to the complex type of water filling, ie, mainly water filling of solution fissure aquifer, whereas the simple type is above the altitude 1 734 m. According to the result derived from the abstraction testing, the main prognosis method of tunnel well yield of orefield is introduced in this paper. And the verification of prognosis method and tunnel well yield is carried out with the reality of the later drainage and dry up in the mining.