The invention discloses a fault detecting and positioning device and method for GIS heating devices at low temperature. The method comprises the following steps: obtaining the sum of heating power ofall heating devices in a substation, namely, a first heating power; judging whether the first heating power is less than a first standard power; if the first heating power is not less than the first standard power, determining that there is no fault in all the heating devices in the substation; if the first heating power is less than the first standard power, obtaining a second heating power in each area in the substation; judging whether each second heating power is less than a second standard power; if there is a second heating power not less than the second standard power, determining thatthere is no fault in all the heating devices in the area corresponding to the second heating power; and if there is a second heating power less than the second standard power, determining that there is a fault in the heating devices in the area corresponding to the second heating power, and determining a faulty heating device. By using the device or the method provided by the invention, the heating devices can be monitored online and in real time, and a faulty heating device can be located quickly and accurately.