A broadcasting method of worked-out section hard roof by remote sensing means includes forming remote sensing network by drilling hole line with interval distance of 15-25 m near last row support at heading stope then erecting transducer and extension sets being all connected to ground host computer in return air and transportation tunnels, repeating said process when each 15-20 m of working face is pushed on, processing collected signals to be separation layer speed by host computer, issuing alarm of roof inbreak by both host computer and extension sets when separation layer valve displayed by any transducer is over threshold. |