Abstract: For PLC power down problem of belt transportation system due to emergency in mine integrated automation system, which makes belt of inverse direction of coal flow fail to stop and results in coal piling accident, a handling method of PLC power down with software-level was proposed. The method judges power down of I/O substation mainly by detecting communication status of ENBT module of remote I/O substation, then stops running of the belt of inverse direction of coal flow accoding to interlocking relationship, so as to make relevant belts stop timely and avoid accidents of coal piling.