Abstract: Imperfect bundle tube monitoring technology may affect the monitoring results，lead to inaccurate data monitoring and influence the accuracy of the“three－zone”division in the gob of working face，in this paper，014N^－₁¹fully－mechanized top－coal caving face in Ruian Coal Mine was taken as the research odject，double－gateway bundle tube monitoring technology was used to monitor the gas concentration，the ORIGIN software was used to process the monitoring data，and finally the variation rule of oxygen concentration at each measuring point and the scope of spontaneous combustion“three－zone”division in the gob of the working face were obtained．The results showed that the improved double－gateway bundle tube monitoring technology was feasible，it improved the effective monitoring time and data accuracy; in the Ruian Coal Mine，the maximum width of the spontaneous combustion zone in 014N₁^－1fully－mechanized top－coal caving face was 37．7 m and the minimum limit advancing speed of the working face was 3．25 m/d．