The invention relates to composite thermal fabric and a dyeing process thereof, which are characterized in that the composite thermal fabric comprises outer layer high-reflectivity back fabric and inner layer low-reflectivity front fabric, wherein a thermal insulation layer is arranged between the back fabric and the front fabric. According to the composite thermal fabric and the dyeing process thereof, provided by the invention, the front and the back of the fabric are respectively made of the high-reflectivity back fabric and the low-reflectivity front fabric, so that the fabric can be overturned and worn inside out; in areas with large temperature difference between day and night, in the hot day, one side made of the high-reflectivity back fabric is worn outside to achieve a cooling effect; in the cold night, the low-reflectivity dark side is worn outside to achieve a thermal insulation effect.