The invention relates to a reusable flat electronic product packaging box and a making method thereof. The packaging box comprises an outer box body and two support pads used for supporting two end parts of the flat electronic product, wherein each support pad is formed by a buffer body and two mortise locks; the buffer body is formed by a center plate and two folded parts; each folded part is formed by a first folded plate, a second folded plate, a third folded plate, a fourth folded plate, a fifth folded plate, a sixth folded plate and a seventh folded plate; one side of the first folded plate is vertically connected with one side of the center plate; the first folded plate, the second folded plate, the third folded plate, the fourth folded plate and the fifth folded plate are vertically folded in sequence; and the folding direction of the second folded plate is opposite to the direction of the center plate, so that the second folded plate and the center plate are respectively located at the upper end face and the lower end face of the first folded plate. According to the invention, the mortise locks are inserted to two ends of the buffer body, thus avoiding the phenomenon of sliding of a product in a clearance between two folded parts. The packaging box is suitable for packaging electronic products such as an English learning machine, material utilization rate is improved, and paper waste rate is reduced.