The utility model discloses a round jet energy dissipater capable of suppressing sudden enlargement and vertical drop. The round jet energy dissipater capable of suppressing sudden enlargement and vertical drop comprises a first transition section connected with a flood discharging tunnel, a rectangular sluice chamber section, a stilling pool, a second transition section and an equal-pore-diameter circular pipe section, wherein the first transition section, the rectangular sluice chamber section, the second transition section, the equal-pore-diameter circular pipe section and the stilling pool are sequentially connected; the pore diameter of the equal-pore-diameter circular pipe section meets an inequation of 0.2B