Abstract: A drive gear shaft structure of a self-moving type mower is provided adjacent to a wheel unit disposed at the bottom portion of a mower, and includes upper and lower housings which co-define a receiving space after assembly thereof; a shaft, a gear, two transmission taper blocks, two securing plates, two securing oil seals, a worm and a trigger rod disposed in the receiving space; and a transmission structure connected to the worm and a transmission spindle of a drive motor of the mower. The structure utilizes motor output power of the cutter of the mower to enable the wheels of the mower to automatically rotate.