A shaft assembling structure includes a shaft hole formed on a motor rotor and a shaft with a shaft end sheathed on a shaft hole of the motor rotor. The shaft assembling structure further includes a direction setting member secured to the top of the motor rotor and embedded with the shaft, and at least one direction setting member disposed at the bottom of the shaft assembling structure and extended into the first direction setting portion of shaft hole. The shaft end of the shaft includes at least one second direction setting portion embedded into the corresponding first direction setting portion. When the second direction setting portion is aligned precisely with the first direction setting portion, the shaft hole of the motor rotor is sheathed on the shaft end of the shaft to facilitate the process of recognizing and confirming the rotating direction of the shaft.