The invention relates to a threshed and redried finished cigarette impurity detection device and method. The device comprises a supporting part, a conveying part, a first impurity removing part, a second impurity removing part, a third impurity removing part, a fourth impurity removing part and a fifth movable impurity removing part, wherein the first impurity removing part, the second impurity removing part, the third impurity removing part, the fourth impurity removing part and the fifth movable impurity removing part are arranged on the conveying part; the first impurity removing part comprises a vibration screen; the second impurity removing part comprises a pneumatic separation impurity removing device; the third impurity removing part comprises a metal detector arranged on the conveying part; the fourth impurity removing part comprises a tobacco impurity characteristic identifying device; and the fifth impurity removing part comprises a movable part, a bearing part arranged on the movable part, and an illumination part arranged on the bearing part. The device is reasonable in overall structure, the multiple impurity removing parts are arranged, impurities of different sizes and types can be separated, and the onerous work of manual impurity sorting is reduced. The finished tobacco impurity yield is increased, the safety of the tobacco product quality is ensured, and the fifth movable impurity removing part is convenient and flexible.