The mechanism of ultrasonic ranging has the advantages of being simple in structure, low cost, high measurement speed, and free from the environmental constrain, such as severe whether. It has been widely adopted even through there are still some shortcomings in the measurement range, such as the measurement interval limitation, wave beam over wide , poor resolution in direction, and unexpected reflection phenomenon in mirror[1-3].The main principle of ultrasonic ranging is to measure transit time that ultrasonic emits through launched probe, more specific, is the total travel time of the ultrasonic wave from the probe passing the target, reflected by the target , and then coming back to the received probe in the same route. The distance between sensor and the target is calculated by the half value of the arithmetic product between the transit time and the speed of propagation of the ultrasonic wave in the medium. The measurement for the transit time includes: Pulse-echo method, Phase difference method, and Frequency difference method [4-6]. Among the methods, the accuracy of the Pulse-echo method is always related to the size of the echo signal amplitude, which is influenced easily by environmental elements. However, it has the advantages of simple measurement circuit, easy implementation, and low cost, which leads to its wide application. Considering the problems of cross interference and aliasing effect, as well as the occasional false triggering phenomenon in the occasions of multiple ultrasonic ranging, this study designed a special ultrasonic ranging finder to avoid them by employing the technology of codec. The experimental conclusion shows that it can be reliably applied to the occasions that multiple ultrasonic range finders are adopted used at the same time.