Abstract: The simulated distance data with high precision, good stability and adjustability are needed in the performance testing of an infrared range finder. The optical fiber as an ideal distance-simulating component is of many excellent characteristics such as high accuracy and good stability, but with the increase of the simulated distance, it shows some shortcomings, i.e. large physical dimension, weak portability and flexibility. To make up for the lack of fiber-delay simulated testing method, the distance- simulating technique based on circuit-delay was studied. The simulated echo producing circuit and simulated echo high precision delay time control circuit corresponding to the method were designed. The inherent delay and error of the system were analyzed. The verification of the simulated test circuits was implemented by Time-to-Digital-Converter circuit and the simulated distance control precision can achieve 0.5 m. It supplements the simulated testing technique for infrared range finders by fiber-delay.