The invention brings forward a leadless ultrasonic energy transducer and a radar ranging system possessing the leadless ultrasonic energy transducer. The radar ranging system comprises a master control device, at least one leadless ultrasonic energy transducer and a display apparatus, wherein the leadless ultrasonic energy transducer is connected to the master control device and uses a leadless piezoelectric material, the master control device generates a voltage excitation signal, amplifies the signal and sends the signal to the leadless ultrasonic energy transducer so that the energy transducer can emit a supersonic wave, the supersonic wave encounters a barrier to be reflected back to the leadless ultrasonic energy transducer, then the supersonic wave is converted a voltage signal and is sent to the master control device, the master control device process the voltage signal so as to acquire the distance between the leadless ultrasonic energy transducer and the barrier, and the display apparatus is connected to the master control device and is used to display the distance calculated by the master control device. The radar ranging system application provided in the invention is based on the ultrasonic energy transducer utilizing the leadless material and realizes system environmental protection. Besides, through an adoption of a high performance signal processing system, the weak piezo-electricity of the leadless material is compensated and the high precision property of the distance determination is realized.