In the domain of precision measurement and sensing technology, laser feedback technology is widely used due to its unique advantages. In order to reduce the impact of deadpath error on the system, a measurement method based on laser feedback effect was proposed, and the full quasi-common-path measurement system was constructed. The working principle and optical structure of the system were analyzed, and the resolution and stability of the system were experimented. The experimental results show that the full quasi-common-path method can improve the system resolution to 2 nm, and it has good stability at different distances and times. It effectively diminishes the influence of environmental fluctuations and significantly compensates for deadpath errors, making it suitable for displacement and vibration measurements in precision machining equipment.