The invention provides FAIMS based on a carbon nanotube ionization source. The FAIMS comprises a PCB and a supporting and fixing board. The internal part of the supporting and fixing board is provided with the carbon nanotube ionization source, a FAIMS chip and a detector which are arranged from an open end to a connecting end in turn. The detector is arranged on the PCB. Channels penetrating through the supporting and fixing board and the PCB are formed among an air inlet, the carbon nanotube ionization source, the FAIMS chip and the detector. The carbon nanotube ionization source comprises a power supply. The positive electrode of the power supply is connected with a counter electrode, and the negative electrode of the power supply is connected with a carbon nanotube electrode. The carbon nanotube electrode comprises a carbon nanotube layer and a substrate. The carbon nanotube layer is arranged at the internal side of the substrate and opposite to the counter electrode. A sample passing channel is reserved between the carbon nanotube layer and the counter electrode. According to the scheme, the carbon nanotube layer can be formed by directly coating the carbon nanotube layer on the substrate so as to be quite easy and convenient.