The invention discloses a gear structure which comprises a shell. Multiple radiating openings are formed in the shell. A sound insulation chamber, a motor, a gear set and a planet gear set assembly are arranged in the shell. The motor is arranged in the sound insulation chamber, a motor output shaft is arranged on the motor, and the motor output shaft extends out of the sound insulation chamber. The motor output shaft is sleeved with a first gear. The gear set comprises a second gear, a transmission shaft, a third gear and an output shaft. The first gear is engaged with the second gear, the second gear is arranged on the transmission shaft in a sleeving manner, and the transmission shaft is fixed to the shell through a bearing seat. According to the gear structure, on one hand, design and manufacturing are facilitated, and on the other hand, the effects of vibration reduction and noise reduction of a gear transmission device are achieved.