The invention discloses a lower-respiratory-tract secretion collecting bottle for a bronchoscope. The lower-respiratory-tract secretion collecting bottle comprises a bottle body, wherein the top of the bottle body is communicated with an air extracting pump through an air suction pipe; the top of the bottle body is communicated with a suction head through a collecting pipe; the air extracting pump is supplied with power by a power supply; the on and the off of the air extracting pump are controlled by a control mechanism. According to the lower-respiratory-tract secretion collecting bottle, when the suction force is excessively high, the pressure in the suction head is suddenly reduced; as a cavity is not communicated with the interior of the suction head, air pressure is higher relative to a through hole; an obstructing block is oppressed to cut off the through hole; the damage to a respiratory tract of a patent as the suction force is too high can be effectively avoided; when a pipeline of a device is blocked, as the air extracting pump continuously works, the air pressure in the bottle body is continually decreased relative to that of an external environment; a sliding block in a sleeve is moved towards a right end; under the traction of a cable rope, an upper conductor sheet and a lower conductor sheet overcome the action of the elastic force of a spring hinge and are not in contact any more; the power supplied to the air extracting pump is disconnected by the power supply; the further damage to the inner wall of the respiratory tract is effectively avoided.