A dual-frequency laser interferometer, as a commonly used precision optical noncontact measurement device, has the advantages of high precision, strong anti-interference ability, and good flexibility. However, factors such as ambient temperature changes and mechanical vibration may affect the accuracy of the measurement results, and the extent of this influence increases with the optical measurement path. To investigate a large-stroke displacement platform ranging system based on a dual-frequency laser interferometer, the measurement principle of a shifting platform ranging system was first studied. Next, the errors existing in the system were analyzed and compensated. Finally, a comprehensive error compensation experiment was carried out on the system, and the short-term compensation reached the order of 10-8 m, with a longer time producing a better compensation effect. The method was more complete than the existing error compensation method, and the compensation was larger.