The invention discloses a method for preparing an interior trim part of a car roof from moxa. The method comprises the following preparation steps: firstly, extracting the moxa and combing downwind to form raw material moxa; adding activated carbon formed by carbonization of elm powder and folium artemisiae argyi into the raw material moxa, hot-pressing by a mold to form a moxa car roof matched with the car roof in shape, wherein the thickness of the moxa car roof is 2-10 mm, and the inner surface of the moxa car roof is corrugated; spraying the back surface of the moxa car roof with a layer of waterproof and moisture-proof heat-insulating aluminum membrane; blending gastrodia elata or natural silk with the moxa to prepare cloth, punching a conical inverted hole in the front surface of the cloth and then covering the front surface of the moxa car roof. The method is simple in process, and the prepared interior trim part of the car roof is good in heat-insulating effect, and can fully absorb odor in the car and send out effective ingredients with sterilization and antivirus functions, thereby preventing bacteria and virus from invading a respiratory tract, preventing influenza virus and playing a role in purifying air.