The invention discloses a three-dimensional heart mapping system and method based on ultrasonic distance measurement. The three-dimensional heart mapping system based on ultrasonic distance measurement includes an ultrasonic crystal, an ultrasound collecting module and an ultrasonic driving module. By adopting a method of combining ultrasonic distance measurement with electromagnetic locating, cloud data of cardiac intima points can be obtained fast in the process of conducting an interventional operation of an intracardiac catheter. When the three-dimensional spatial position points of the cardiac intima are mapped, the distance information between the interventional catheter and the cardiac intima is provided through an ultrasonic distance measurement method. The distance is calculated through an ultrasonic echo detection mode, and the ultrasonic echo detection mode has the advantages that the speed is high and the precision is high; the distance information can be in communication with an upper computer through a serial port query mode. The distance between the interventional catheter and the cardiac intima can be obtained through a non-contact mode, communication with the computer is achieved, and a foundation is laid for restoring the three-dimensional spatial position information in combination with electromagnetic locating to obtain a three-dimensional heart chamber model.