The invention provides a grouting reinforcement treatment method for a mid-depth goaf below a building foundation. The method mainly includes the steps that the grouting boundary range is determined through calculation, the grouting drilling depth is determined through a water injection test, grouting drilling, a grouting pump, a grouting rod and a hole packer are involved, the grouting boundary range is determined through theoretical calculation and the water injection test, grouting parameters and the grouting process are designed, and grouting reinforcement effect quality detection and settlement monitoring are conducted. The building foundation treatment method suitable for the coal mine goaf is provided. The method is characterized in that the grouting range is determined through theoretical calculation by looking up exploration and geographical data; the grouting drilling depth is determined through the water injection test; the corresponding grouting parameters are designed, grouting equipment is selected, and the grouting process is determined; drilling coring is conducted after one month after grouting construction, and grouting quality detection and surface deformation monitoring are conducted. The method has the beneficial effects that the damaged rock stratum and loosened rock of the coal mine goaf on the lower portion of a building are reinforced, residual displacement and deformation of overlaying rock on the upper portion of the goaf are effectively controlled, and normal use of the building is guaranteed.