An electronic device and an electronic device assembly method. A through hole is provided in a rear cover. An inner wall of the through hole protrudes to form an annular flange. A camera decorative member is designed to include an inner decorative member and an outer decorative member. The outer decorative member is arranged on a side of the rear cover facing away from a middle frame and is connected to the annular flange by a bonding layer, and the inner decorative member is fastened to a side of the outer decorative member facing the middle frame, so that a gap between the outer decorative member and the annular flange can be blocked by the bonding layer, and the bonding layer is used for sealing to prevent water in an external environment from entering the electronic device through space between the outer decorative member and the rear cover.