The invention relates to a double-power supply automatic switching device of a pole top switch, which is used for controlling the automatic switching of the pole top switch. The double-power supply automatic switching device of the pole top switch comprises a first switch switching control module and a second switch switching control module, wherein the first switch switching control module detects the voltage condition of a main power supply side power supply line by a first voltage detecting module; when the voltage of the main power supply side power supply line is lower than a preset threshold value, the first switch switching control module controls the pole top switch on the main power supply side power supply line to switch off; the second switch switching control module detects the voltage condition of a user load side power supply line by a second voltage detecting module; and when the voltage of the user load side power supply line is lower than a preset threshold value, thesecond switch switching control module controls the pole top switch on a backup power supply side power supply line to switch on. The embodiment of the invention can finish controllable automatic switching on the pole top switch on the main power supply side power supply line and/or backup power supply in a double-power supply power distributing scheme with further distance of a main power supplyand a backup power supply, not only protects an important user load from the influence of unavailable normal power supply of the main power supply but also prevents the risks of expanded power failure range and overlong power failure time.