Abstract: The Beijing Free Electron Laser (BFEL)is a Compton regime, IR FEL oscillator, using the electron beam from a 30MeV rf linac. One of the features of this project is that a microwave electron gun is adopted as the high brightness injector. In this paper, first the general layout of the facility and the main physical parameters are given; then the design goals of the electron beam and lasing characters of the FEL are presented by the analytical and simulation methods. Then we set forth the technical features, the desired goals and experimental results for the sub-systems of BFEL, which are microwave gun, accelerator and microwave system, modulator, transport system, undulator, optical cavity,electron beam diagnostics,collimation,spontaneous emission and laser experiments.