The present invention relates to a thermal insulation method and a thermal insulation apparatus for a transformer substation portable electronic device battery, and belongs to the technical field of power supply equipment. The technical scheme comprises that: an electric heating film (1) and thermal insulation cotton (7) are arranged inside a apparatus fabric sleeve (8), the apparatus fabric sleeve is arranged inside an elastic transparent plastic sleeve (9), one outer surface of the apparatus fabric sleeve and one inner surface of the elastic transparent plastic sleeve are tightly and integratedly fixed, a gap exists between the other outer surface of the apparatus fabric sleeve and the other inner surface of the elastic transparent plastic sleeve, a portable electronic device is inserted into the gap, a battery side of the portable electronic device is tightly close to the apparatus fabric sleeve, and a keyboard side or a screen side of the portable electronic device is tightly close to the elastic transparent plastic sleeve. According to the present invention: a structure is simple, a maintenance cost is low, a continuous thermal insulation effect can be provided for the transformer substation portable electronic device battery under an outdoor low temperature state, and use efficiency and a service life of the transformer substation portable electronic device battery under an outdoor low temperature state can be improved.