Abstract: The overlying 13125 protected mining face conducts underlying 13165 gob after a certain distance mining through the fissures. To solve the problem that the carbon monoxide produced by the residual coal oxidation due to underlying coal seam goaf flows to 13125 working face retention tube by gas extraction in upper corner retention tube, we proposed the water injection cooling technology, and carried out the water injection study at the top of 13165 goaf by boreholes. The results showed that the carbon monoxide detected by the corner retention tube on 13125 working surface after water injection and cooling was reduced to 8×10^-6 from the maximum of 116×10^-6 before water injection; with the increase of the number of drilling construction, the amount of water injection is increased, and the carbon monoxide in the tube is also decreased.