The invention relates to a tool for assembling a quick switch mechanism and an arc-extinguishing chamber. The tool comprises a linear guide rail. A mechanism installing base and an arc-extinguishing chamber installing base are assembled on the linear guide rail in a guiding way. The mechanism installing base and the arc-extinguishing chamber installing base are respectively provided with a fixing structure used for realizing coaxial centering of the quick switch mechanism and the arc-extinguishing chamber. The assembling tool also comprises a driving mechanism which is used for driving an insulator to rotate, wherein the two axial ends of the insulator are respectively connected with the quick switch mechanism and the arc-extinguishing chamber through forward and reverse threads. The quick switch mechanism and the arc-extinguishing chamber are respectively assembled on the mechanism installing base and the arc-extinguishing chamber installing base firstly in use, then the two axial ends of the insulator are partially screwed into the quick switch mechanism and the arc-extinguishing chamber, and then the insulator is driven to rotate by the driving mechanism and the insulator is further screwed into the quick switch mechanism and the arc-extinguishing chamber so that the assembling efficiency is higher, the centering performance of the assembled component is better and the structural strength of the assembled component is more uniform.