This high and low level controller can realize the function of liquid level high and low control: when the container liquid level is too low, the low liquid level alarm signal sent by the low liquid level sensor is triggered to trigger the controller to close the relay to start the water pump Add the liquid level, when the liquid level reaches a certain height, the high liquid level sensor sends out a signal to trigger the controller to disconnect the relay and automatically stop the water pump to work in a cycle. Thereby, the function of automatic control of the container liquid level is realized, and the container liquid level is kept stable.