The utility model discloses an axial force balancing device of a vertical multi-stage centrifugal pump. The axial force balancing device is characterized in that a lower friction ring is arranged at the position where a pump contacts with the outer edge of an impeller inlet, an upper friction ring is arranged at the position where the pump contacts with the upper end of an impeller outlet, a throttling ring is arranged on a rear impeller cover plate, and a fixed plate corresponding to the throttling ring is fixed on a pump shaft in the back of an impeller. A suitable gap formed between the fixed plate and the throttling ring on the rear impeller cover plate is guaranteed when the axial force balancing device is assembled. When the axial force balancing device works, a rotator part floats up and down along with changes of pressures in the front of the impeller and in the back of the impeller, the gap between the throttling ring on the rear impeller cover plate and the fixed plate changes, and accordingly, self-balancing of axial force is realized by changing pressure difference in the front of and in the back of the impeller.