Abstract: Because of air-leaking channels existing between each goaf, there is a difficult problem to find the source of CO under the condition of multi-goaf. Through drilling borehole to take and test gas, releasing SF₆ to find air-leaking channels, the paper proposes a method to find CO gas source under the condition of multi-goaf, taking nitrogen injection and grouting sealing measures can effectively inhibit toxic gas dispersion in adjacent goaf.