The invention discloses a supporting device of a subway blower motor. A flange plate is fixed on the end wall of an internal support cylinder; the internal support cylinder at the upper end of a motor is short; the internal support cylinder at the lower end of the motor is long; most of the upper end of the motor exposes out of an internal support cylinder wall on the upper end of the motor; the internal support cylinder is fixed on the inner wall of an external support cylinder by connecting plates which are uniformly fixed on the outer wall and have the same length as that of the internal support cylinder at this position; mounting holes and accommodating holes are formed in the internal support cylinder walls at a lifting ring position at the lower end of the motor and in the connecting plates corresponding to the symmetric positions at both ends of the lifting ring position respectively; bolts are fixed in the mounting holes in the internal support cylinder walls, are fixed in the lower end of the motor and are located in the accommodating holes of the connecting plates. The supporting device is adopted to mount the subway blower motor, has high supporting strength, reduces vibration of the blower, plays a role of diversion, improves the efficiency of the subway blower, enables the motor to have a good heat dissipation effect, reduces the energy consumption of the subway blower.