Abstract: Refining biogas can be used as vehicle fuel and its quality is similar to natural gas. Refining biogas is becoming one of the important branches of energy field. The frame and working process of biogas refining system for obtaining vehicle fuel were discussed. Among them, the main device-hollow fiber polyimide membranes separation module was devised by our special request. And the other devices for removing water vapour, sulfureted hydrogen, oxygen, ammoniate were designed by ourselves. The primary experiments were carried out under the 40℃, 0.6 MPa reaction conditions. The components of biogas were tested before and after refining. The results showed that CH4 increased from 63.47% to 87.21%, CO2, O2, H2S and dew point decreased from 28.22% to 9.23%, from 1.16% to 0.04%, from 30×10-6 to 10×10-6 and from 12℃ to -19℃, repectively. The research and experiment of biogas refining system provide theoretical bases and practical references for the development of membrane separation system fit for big or moderate biogas engineering.