The invention provides an efficient SCR (selective catalytic reduction) denitration structure and an efficient SCR denitration method capable of reducing a sulfur dioxide/sulfur trioxide conversion rate. The SO2/SO3 conversion rate is reduced while efficient operation of an SCR reactor is guaranteed. The method comprises the following steps: treating flue gas of a hearth by an economizer, enabling the flue gas to enter the SCR reactor and pass through a first layer of catalyst to perform denitration reaction, removing most of NOx and consuming most of NH3, enabling the flue gas to enter a secondary air pre-heater, heating environment air pumped by an air feeder and in the secondary air pre-heater, enabling cooled flue gas to pass through a second layer of catalyst and a third layer of catalyst sequentially to perform denitration reaction continuously and then enter a primary air pre-heater, further heating the environment air in the primary air pre-heater and discharging; feeding the pumped environment air into the primary air pre-heater by the air feeder, exchanging heat with the flue gas, enabling the environment air heated to a certain temperature to enter the secondary air pre-heater, further heating the environment air by the flue gas, and feeding the heated air into a combustor to become the air required by hearth combustion.