A case assembly and an electronic device are provided. The case assembly includes a metal case and a plastic cladding body. The metal case includes an inner side and an outer side, the inner side is opposite to the outer side. The metal case further includes a channel which is concavely disposed on the inner side to divide the inner side into a plurality of thermal insulation areas. The plastic cladding body is disposed on the metal case, and completely covers the outer side of the metal case. The electronic device includes a case assembly and a plurality of heart sources. The heart sources are corresponded to the thermal insulation areas on the inner side of the metal case respectively. Thus, the case assembly and the electronic device are able to prevent the heat produced from elements effect each other.