The present invention discloses a test device and test method for the noise reduction headphone. The test device comprises: an enclosed cavity, a noise source, a test panel, a measuring microphone and a measure comparison module connected with the measuring microphone. The sound emitted from the noise source is sealed within the enclosed cavity. The test panel can cooperate with the noise reduction headphone to form a coupling cavity in the test. The test panel has a sound guiding hole in the common part with the enclosed cavity for transmitting the sound of the noise source into the interior of the coupling cavity. The test panel also has a mounting hole, and the measuring microphone is mounted on the mourning hole towards the direction of the coupling cavity. The measuring microphone records noise signals before and after the noise reduction function of the noise reduction headphone is activated. The measure comparison module receives the signals recorded these two times by the measuring microphone and performs comparison processing to obtain noise reduction amount of the noise reduction headphone. The technical solution of the present invention solves the problem of noise pollution caused by high-power external noise sources to the surrounding environment during the test process of noise reduction amount of the headphone, meanwhile, no special shielding room is required, and the requirement on test environment is relieved.