The invention discloses an upper decorative plate and lower decorative plate fixing structure, which comprises an upper decorative plate outer plate, an upper decorative plate skeleton, a lower decorative plate outer plate and a lower decorative plate skeleton, wherein the side surface of the upper decorative plate skeleton is propped against the inner side surface of the upper decorative plate outer plate; a tapered boss is convexly arranged on the side surface of the upper decorative plate skeleton, close to the connected part of the upper decorative plate outer plate and the upper decorative plate outer plate, along the direction back to the upper decorative plate outer plate; the top end of the lower decorative plate skeleton extends upwards to form a pair of U-shaped grooves opposite to the tapered boss; and the tapered boss is supported between the upper decorative plate outer plate and the U-shaped grooves. By adopting the structure of the tapered boss and the U-shaped grooves, the upper decorative plate skeleton and the lower decorative plate skeleton are connected and fixed, so that the strength of the connected part of the upper decorative plate skeleton and the lower decorative plate skeleton is improved, closer fit between an upper decorative plate and a lower decorative plate is ensured and the reliability of the connected part of the upper decorative plate and the lower decorative plate is improved.