The invention discloses a high-airtightness passive house and a construction process thereof. The high-airtightness passive house comprises a wall body, wherein a roof is mounted at the top end of the wall body, a solar panel is mounted at the top end of the roof, a fresh air assembly is mounted at the top of the wall body, and an air exchange chamber is formed in the middle of the top of the wall body. According to the high-airtightness passive house, by arranging the air exchange chamber, an inner air cavity, an outer air cavity, an air conveying groove, an upper air hole, an arc-shaped baffle, a lower air hole, an air inlet pipe and an air inlet hole, the lower air hole is opened, and air enters the air conveying groove, the outer air cavity, a connecting air pipe and the inner air cavity from the lower air hole; and finally 2, by arranging the connecting air pipe, an exhaust pipe and an exhaust baffle, cold air in the air exchange chamber is preheated through waste heat of hot air passing through the inner air cavity and the outer air cavity, the preheated air enters a room through the air inlet hole, the temperature difference between outdoor air and indoor air is reduced, fresh air can enter the room during refrigerating and heating, thus the indoor air is fresher, and the environment is more comfortable.