The invention relates to a water drainage system, in particular to a smart water suction pump capable of automatically controlling water drainage. The smart water suction pump comprises a controller, a water level sensor, a water pump, a water level sensor detection circuit and a water pump current detection circuit; and the water level sensor detects the water level through the water level pressure, the water level sensor transmits a received water level signal to the controller through the water level sensor detection circuit, the controller controls opening of the water pump by judging whether the water level signal reaches to a preset value or not, the controller controls closing of the water pump according to the electric current of the water pump detected by the water pump detection circuit, and the controller supplies power through a power supply module. The water suction pump adopts the water level sensor to detect the water level, and controls the operation situation of the water pump through the water level information, and water is drained thoroughly.