The ultrasonic sensor is developed by using ultrasonic characteristics.Ultrasonic is a kind of vibration wave frequency is higher than the sound wave, has the advantages of high frequency, short wavelength,the diffraction phenomenon of small, especially the good direction, can become rays and directional propagation characteristics. A few years ago, in the field of sensor technology, the ultrasonic sensor is alwaysalternate choice. The new technology makes the ultrasonic sensortoday are very durable and has a sense of accurate, these newenhancements to expand new areas of application, completely beyond the application of traditional ultrasonic sensor.