The invention discloses an odometer calibrating device. A control box comprises a DSP (Digital Signal Processing) control module and an input/output terminal, wherein a code disk with a magnetic steel sheet is positioned on a rotary shaft of a stepping motor and is driven to rotate by the rotary shaft; a hall sensor is positioned beside the code disk with the magnetic steel sheet, is connected with the DSP control module and is used for transmitting a low-level pulse signal generated by a hall effect to the DSP control module; the DSP control module is connected with the stepping motor through a motor driver and is used for controlling the rotation of the stepping motor; and the DSP control module is connected with the input/output terminal. The odometer calibrating device can be used for driving a vehicle odometer to rotate at a required running speed in a specified running speed range according to the transmission ratio of a vehicle output shaft, recording the running speed, calculating the road haul and verifying the functional accuracies of the vehicle odometer and a vehicle-mounted inertia positioning and orientating navigation device odometer.