The invention relates to an anaerobic reactor, in particular to a double-path circulation full-mixing type anaerobic reactor, mainly comprising a reactor body, a feeding device, a circular stirring device, a drainage device, a safety protection device, an effluent device, a heating device, a detection control device, a methane collection device and the like. The double-path circulation full-mixing type anaerobic reactor is provided with an internal circulation stirring device and an external circulation stirring device; the two circular stirring devices are combined to stir materials, internal circulation stirring plays a main role, while external circulation stirring plays an assistant role, so that the reactor has the characteristics of effectively trapping slurry, having high yield, obviously reducing operation cost, remarkably improving effluent quality and the like.