The invention discloses a membrane separation device comprising a housing, a rotor arranged in the housing and a separation chamber arranged inside the rotor, wherein the internal surface of the housing is a cambered surface; at least one medium inlet and at least one medium outlet for discharging a medium separated out are formed on the housing; at least two contact terminals which are always in sliding contact with the internal surface of the housing are arranged on the external surface of the rotor; the external surface of the rotor and the internal surface of the housing are formed into a sealed independent cavity between every two adjacent contact terminals; the inner hollow part of the rotor is used as a medium storage chamber; a film is filled inside the separation chamber; one-way valves are arranged on the outer wall of the separation chamber, are corresponding to the independent cavities and are communicated with the independent cavities; a medium outlet is formed on the inner wall of each separation chamber and is corresponding to the medium storage chamber; the medium storage chamber is communicated with the medium outlet of the housing. The membrane separation device provided by the invention has the advantages that the separation chamber is arranged inside the rotor, the film is used for separation, the structure is more compact and complex gas (liquid) pipelines are not needed any more.