Pneumatic motor device with high-low speed conversion

The invention discloses a pneumatic motor device with high-low speed conversion. A blade pneumatic driving motor spindle is sequentially coaxially sleeved with a first inner gear in an emptying manner and is provided with a driving gear; a second inner gear is mounted on an output shaft; the output shaft and the blade pneumatic driving motor spindle are coaxially mounted; a first gear clutch engaged with a circumference gear on the lateral face of the first inner gear is mounted on a spindle of an air cylinder; a second gear clutch engaged with a third inner gear is mounted on the spindle of the air cylinder; a planet shaft is sleeved in the third inner gear in an emptying manner; the both ends of the planet shaft are respectively provided with a first planet gear and a second planet gear; the first planet gear is engaged with the first inner gear; and the second planet gear is engaged with the second inner gear. According to the pneumatic motor device provided by the invention, a planet gear speed reducer is switched between an ordinary gear train and an epicyclic gear train; a speed reducing ratio of the ordinary gear train is small; and a speed reducing ratio of the epicyclic gear train is large, so that the speed conversion can be realized.