The invention discloses a high-altitude down jacket, and relates to the technical field of clothing, the down jacket comprises a down jacket body, the down jacket body is composed of a jacket body, a cap and sleeves, the jacket body is provided with armholes, the sleeves are fixed on the armholes, shaping strips are arranged in the edges of the armholes, and the armholes are supported by the shaping strips to keep an arched state; in the arched state of the armhole, a micro space exists between the
peripheral area of the armhole and the
human body; passive gradient breathable cloth pieces are spliced in the armpit areas of the down jacket body, one part of the passive gradient breathable cloth pieces are spliced in the sleeves, and the other part of the passive gradient breathable cloth pieces are spliced in the jacket body; the passive gradient breathable cloth piece comprises a
moisture-conducting lining layer making contact with the
human body, a breathable surface cloth layer making contact with the outside and a fluffy cotton layer clamped between the
moisture-conducting lining layer and the breathable surface cloth layer, and the air permeability of the breathable surface cloth layer is larger than that of the
moisture-conducting lining layer. The micro-space is matched with the passive gradient breathable cloth piece, so that the loss of heat of a body can be effectively reduced while moisture is efficiently discharged.