The invention discloses a rotary-cut atomization SCR denitration method and an apparatus thereof. The apparatus comprises a denitrating tower body and a plate-type catalyst layer arranged along the periphery of the denitrating tower body, and a flue gas channel is formed by the plate-type catalyst layer; a flue gas introduction pipeline is arranged along the circumference tangential direction on a side wall of the bottom of the denitrating tower body; preliminary mixing of the flue gas and ammonia gas injected from an eddy flow atomizing nozzle is carried out in the flue gas introduction pipeline, then a mixture is injected into the flue gas channel along the circumference tangential direction of the denitrating tower body, then meets with the ammonia gas injected from the eddy flow atomizing nozzle of the flue gas channel, because that the ammonia gas in the flue gas channel is injected along the circumference tangential direction, and the flue gas is mixed mutually with the ammonia gas, and the mixture enables spiral rising in the tangent circle mode along the inner circumference of the flue gas channel. According to the apparatus, under prerequisite that high efficiency denitration is ensured, catalyst amount is less, compared with the prior art, a denitrating tower structure is simple, cost is low, denitration efficiency is high, energy consumption is low, ammonia escape is reduced, secondary pollution is avoided, and economic benefit is obviously increased.