The invention relates to a special fixing device for the air permeability flow rate disc detection of tobaccos. The special fixing device is characterized by comprising an upper base seat and a lower base seat which are respectively and fixedly arranged on a machine frame, wherein an upper positioning block provided with a center through hole is connected onto the upper base seat and can be upwards turned around a turning shaft pin, a lower positioning block provided with a center through hole is arranged on the lower base seat, in addition, the upper surface of the lower positioning block isprovided with a cylindrical sinking cavity, a flow rate disc to be measured can be placed between the upper positioning block and the lower positioning block, pressure measuring openings communicatedwith the center through holes of the corresponding positioning block are respectively arranged on the side walls of the upper positioning block and the lower positioning block, and the lower matchingsurface of the upper positioning block and the upper matching surface of the lower positioning block are respectively provided with sealing rings. Through the special fixing device, the air permeability flow rate disc is fixed, is tightly clamped by an elbow clamp and is sealed by rubber sealing rings, only corresponding fittings in the upper positioning block and the lower positioning block needto be replaced for different flow rate standard elements, and in addition, different-type air permeability flow rate discs of different manufacturers can be fast replaced through opening the elbow clamp and turning the upper positioning block of the flow rate disc around the turning shaft pin to be opened.