The utility model provides a device of escape ammonia concentration in survey flue gas denitration device, the device comprises flue gas collection system and ammonia nitrogen analysis appearance. Be used for the escaping entrapment of ammonia of flue gas collection system, ammonia nitrogen analysis appearance is used for the escape ammonia determination after the entrapment. Flue gas collection system includes flue gas collection system (1), absorption tube (2) and heating sampling rifle (3), during heating sampling rifle inserted the flue, flue gas collection system was connected through last one -level absorption tube to the one end series connection multistage absorption pipe of heating sampling rifle outside the flue, have in the heating sampling rifle flue gas filtering material (4), flue gas filtering material in the flue gas by heating sampling rifle in the flue is through the multistage absorption pipe of establishing ties, flue gas to flue gas collection system. The utility model discloses utilize ammonia nitrogen analysis appearance to replace manual color development to compare and carry out detection and analysis, reduced artifical error. The utility model discloses the device is simple and convenient, and the testing result of the deNOx systems ammonia escape concentration that obtains is more accurate, stable.