The invention relates to a low-level waste liquid treating system. The low-level waste liquid treating system comprises a raw water tank, a first conveying mechanism, a membrane component group including at least one membrane component, a water feeding pump and a high-pressure pump, wherein the first conveying mechanism is communicated between the raw water tank and the membrane component group; the water feeding pump and the high-pressure pump are both assembled on the first conveying mechanism; the membrane component group is provided with a liquid inlet, a first liquid outlet and a second liquid outlet which are intercommunicated; the low-level waste liquid treating system further comprises a water producing tank and a concentrated water tank; the water producing tank can be communicated with the first liquid outlet; the concentrated water tank can be communicated with the second liquid outlet; the raw water tank can be communicated with the first liquid outlet and the second liquidoutlet; when preset flushing conditions are reached, the water feeding pump works, and the high-pressure pump shuts down; the water producing tank and the concentrated water tank are respectively disconnected with the first liquid outlet and the second liquid outlet; the raw water tank is communicated with the first liquid outlet and the second liquid outlet; and the membrane component group is flushed by liquid in the raw water tank. Continuous operation of a subsequent system can be ensured, and energy consumption of per ton water in the system and equipment burden are reduced.