The invention provides a high and low-speed input dual-mode transmission device. The high and low-speed input dual-mode transmission device comprises a supporting body. The two ends of the supportingbody are provided with an output shaft and an input shaft correspondingly. An input small gear is arranged on the input shaft. An output big gear is arranged on the output shaft. An intermediate shaftis further arranged on the top surface of the supporting body. The two ends of the intermediate shaft are provided with an intermediate small gear and an intermediate big gear correspondingly. The intermediate small gear is engaged with the output big gear. The intermediate big gear is engaged with the input small gear. The output shaft and the input shaft are coaxially arranged. The end, close the input shaft, of the output shaft is in key connection with an output shaft clutch gear. The input shaft is in key connection with a sliding sleeve. An overrunning clutch is arranged on the output shaft. A ratchet wheel is arranged on the overrunning clutch. An energy storage torsion spring is arranged on the output shaft. A supporting frame is arranged on the supporting body. The supporting body is provided with a detent. A shifting rod is arranged on the output big gear. Through the above structure, the high and low-speed input dual-mode transmission device realizes direct driving transmission during high-speed input and ensures the requirements for the output rotating speed, torque and efficiency through speed reduction, torque increase and energy storage during low-speed input.