The researches about upgrading of methane from biogas by pressure swing absorption are introduced in this paper. Biogas contains 55~70% methane (CH4) which is the main component of natural gas. If other components of biogas are removed, biogas is upgraded to SNG (Substitute Natural Gas). The processes of upgrading of methane from biogas by PSA or VPSA (Vacuum Pressure Swing Adsorption) are presented. Different techniques which are used for upgrading of biogas are evaluated. Finally, prospect about this process is made.