The invention provides an anti-disengaging device of a torque rotational speed-up tool. The device comprises a tool shell and a drill bit base connected with the lower end of the tool shell. The tool shell and the drill bit base are connected in a clearance fit mode. The lower end of the tool shell is provided with a tool shell groove ring, the upper end of the drill bit base is provided with a drill bit base groove ring, and an anti-disengaging jump spring is arranged between the tool shell groove ring and the drill bit base groove ring. By means of the anti-disengaging device of the torque rotational speed-up tool, the torque rotational speed-up tool can be prevented from sliding off, and the situation that drilling accidents are caused because parts in the drill bit base and the tool and a drill bit fall into a well is prevented. Compared with the prior art, the anti-disengaging device has the advantages of being simple and compact in structure, high in shearing strength, high in reliability and easy and convenient to assemble and disassemble.