The invention relates to a power-source-free self-locking emergency pressure relieving, isolating and flame arresting device in a dust collecting and gas exhausting pipeline. The device comprises the dust collecting and gas exhausting pipeline, a first gas exhausting barrel, a second gas exhausting barrel, a balance weight block, a rotation shaft, a small turning plate, a large turning plate and a turning plate shackle, wherein the first gas exhausting barrel and the second gas exhausting barrel are both arranged on the dust collecting and gas exhausting pipeline, the rotation shaft is arranged on the dust collecting and gas exhausting pipeline, the balance weight block, the small turning plate and the large turning plate are all connected to the rotation shaft, the small turning plate and the large turning plate are arranged on the same plane, the turning plate shackle is arranged on the dust collecting and gas exhausting pipeline and right under the rotation shaft and used for locking the small turning plate. Compared with the prior art, the device can respond in time to cut off spread of flame and explosion when pressure anomaly happens in the dust collecting and gas exhausting pipeline and can timely relieve pressure generated by combustion explosion in a small range; in the process, power and other energy are not used, self safety of the device is guaranteed, and the power-source-free self-locking emergency pressure relieving, isolating and flame arresting device is an intrinsically safe device.