The invention discloses an ammonia measurement device for denitration of a flue gas pipeline. The device comprises a first hose, wherein an air inlet end of the first hose is connected with the flue gas pipeline through a sampling gun; an air outlet end of the first hose is connected with a heat exchanger; a right side of the heat exchanger is connected with a warm air blower; a right side of the warm air blower is connected with an air filter element; the air filter element is connected with a first absorption bottle through a second hose; a temperature sensor is arranged in the second hose and connected with the warm air blower through a control system; an air outlet end of the first absorption bottle is connected with a second absorption bottle; an air outlet end of the second absorption bottle is connected with an air pump. A thermal insulation layer can reduce heat loss of a flue gas sample; the heat exchanger is used for heating the flue gas sample by utilizing flue gas temperature, so that energy conservation and emission reduction are achieved; the warm air blower can ensure that the flue gas sample is kept at an optimal temperature, so that the flue gas sample can be completely absorbed by absorption liquor; the air filter element can be used for carrying out secondary filtration on the flue gas sample; a valve is opened to enable the absorption liquor of the absorption bottles to flow into a collecting bottle, and the operation is safe and convenient.