The 8 m laser interferometer prototype facility is currently being constructed at the Institute of Mechanics, Chinese Academy of Sciences in Beijing, China. It aims to perform laser interferometer experiments and pico-meter precision detection and calibration for Taiji pathfinder mission. The seismically isolated ground and passive vibration isolation are interconnected and the optical benches are stabilized by them, which can form two low-noise testbeds inside a 40 m(3) ultra-high vacuum system. An on-ground laser interferometer demonstration used for satellite-satellite tracking will be constructed. In this article, the experimental facility and the employed methods will be described, and the technical details of subsystems will be covered in future papers.