A drive source of a camera lens designed with built-in drive motor inside the camera lens mount delivers benefits of eliminating runout occurring during the telescopic movement of the telescopic lens, and simplifying the parts assembly process. The drive source of camera lens comprises a coil stator installed directly to the inside of the camera lens mount, the spindle of the magnetic ring rotor screws onto the rotation-proof telescopic lens, so as to rotate the spindle of the magnetic ring rotor to drive the telescopic lens with external thread. The present invention allows the camera lens to acquire a built-in drive source, eliminates the runout that occurs during the drive of telescopic lens, and simplifies the assembly process.