The utility model discloses a liquid nitrogen-vat ultrasonic level measuring and displaying device which consists of an ultrasonic transmitting probe, an ultrasonic receiving probe, a level displaying and controlling system, an ultrasonic transmitting circuit, an ultrasonic receiving circuit and an LED, wherein, the ultrasonic transmitting circuit, the ultrasonic receiving circuit and a controlling chip are connected to form the level displaying and controlling system which takes the shape of a bottle stopper and is suitable to be fixed in the center of the opening of the liquid nitrogen vat; the ultrasonic transmitting probe and the ultrasonic receiving probe are under the level displaying and controlling system in parallel; and the LED is positioned above the level displaying and controlling system. The liquid nitrogen-vat ultrasonic level measuring and displaying device has the advantages of convenient installation, no contact, no pollution, high precision, large measuring range, visible result reading and the like, thus being capable of providing better support for the tests and clinical work.