An electrical device having thermal isolation function includes a housing, a heat-generating source, a heat-conductive member, and a thermal isolation plate. The housing includes an accommodation space therein, an inner surface and an outer surface which is opposite to the inner surface. The heat-generating source is disposed in the accommodation space. The heat-conductive member is disposed in the accommodation space, and is in contact with the heat-generating source. The thermal isolation plate is disposed between the heat-conductive member and the inner surface of the housing, and the thermal isolation plate is formed with a vacuum chamber therein.