Device capable of circularly cleaning MBR (Membrane Biological Reactor) membrane unit in offline way

The utility model relates to a device capable of circularly cleaning an MBR (Membrane Biological Reactor) membrane unit in an offline way. The device comprises a circular cleaning system, an online monitoring system, a drug adding system, an aerating system and a heating system. The device provided by the utility model has an automatic drug replenishing-adding function and a circular cleaning function when the membrane unit is in an offline state, a flux, a liquid level and the transmembrane pressure can be automatically monitored, and the cleaning effect and the cleaning time can be automatically judged and controlled by a PLC (Programmable Logic Controller); the cleaning speed can be effectively accelerated, and the liquid medicine consumption can be effectively reduced; and the offline cleaning efficiency of a membrane can be improved, and the device is particularly suitable for use in a low-temperature or serious membrane pollution condition in winter.