A selective catalytic reduction (SCR) denitration stream turbulence device comprises a mixer in an SCR denitration device; a steam turbulence device body is connected to the rear part of the mixer in the SCR denitration device, and comprises a casing; flanges are arranged at the two ends of the casing, and connected with the mixer in the SCR denitration device at the front part and equipment at the rear part respectively; a primary baffling device and a secondary baffling device which are vertically arranged in the axial direction in sequence are arranged in the casing; the space between the primary and secondary baffling devices is used for steam mixing; through two-stage steam turbulence mixing in the steam turbulence device body, NOx in flue gas and a reactant are sufficiently mixed, so that an efficient reaction under the catalytic action can be guaranteed when NOx and the reactant enter a subsequent denitration reactor, and ammonia escape can be avoided.