A kind of ultrasonic telemeter based on AT89C205 is introduced. This telemeter is provided with some merits such as low cost and high-accuracy because of the ultrasonic wave characteristic. The hardware principle electric circuit and the main software design idea are showed. The simulation of the main part of the hardware has been done with Pspice. At last, according to the theoretical analysis and the experience some improvements of the design are made. The system has achieved the anticipated effect.