1. A vertebral body distraction tool, comprising a tool body and a tool cap, wherein the tool body comprises an inner core, an outer sleeve and a distraction ball; the inner core is threadedly connected inside the outer sleeve; an upper end and a lower end of the inner core both extend to the outside of the outer sleeve; the lower end of the inner core is provided with a tapered stapling head; the distraction ball is fitted over the inner core between the tapered stapling head and the outer sleeve; the tool cap comprises an upper tool cap and a pressure cap; the upper tool cap is of a cylindrical structure; a lower end of a cavity of the upper tool cap is connected to an upper end of the outer sleeve; the upper end of the inner core extends to an upper end of the cavity of the upper tool cap; the pressure cap is engaged with and slidably connected to the upper end of the inner core; the pressure cap is engaged with and slidably connected to the upper tool cap; the pressure cap slides along the inner core and the upper tool cap in an axial direction; when the pressure cap slides up along the axial direction of the upper tool cap to release the engagement and slidable connection with the upper tool cap, the pressure cap still keeps the engagement and slidable connection with the inner core; and when the tapered stapling head moves close to the lower end of the outer sleeve, the distraction ball performs distraction.