Abstract: Provided are a rotary shaft of a three-dimensional printing filament spool holder, a three-dimensional printing filament spool holder, and a three-dimensional printer, comprising a fixed tube and a sleeve assembly sleeved outside the fixed tube and being capable of rotating relative to the fixed tube. The sleeve assembly is elastically connected to the fixed tube through an elastic member, the relative rotation between the sleeve assembly and the fixed tube causes the elastic member to generate elastic deformation, and the sleeve assembly is configured for being sleeved in a three-dimensional printing filament spool.