The invention provides a water level intelligent control system which is used for the water level control of low cadmium accumulation cultivation farmland; in the condition of the single water level control, when the water level needs to be controlled, water level control node in single water level controlling module is instructed, the corresponding IO port outputs the low level, a fifth optical coupling relay and a sixth optical coupling relay are set, a buoy control module obtains electricity, thus automatic control of the water level is realized according to buoy trip; in the condition of multiple water levels control, in multiple water levels module, multiple buoy control modules are connected to the different IO ports of the water control node, each the buoy control module carries different buoy trip, the water level control node outputs low level only to the one IO port in a certain period, in the rest of the period, the high level is output, thus only one intelligent module works in the period, the water level is determined by the buoy switch trip, and then the automatic control of multiple water levels is realized.