The invention provides a circuit layout structure of a GIS (gas-insulated metal-enclosed switchgear) power distribution device. The manner that circuit connection among complete strings in the prior art is mutually independent is discarded, adjacent circuit breakers at corresponding positions and between adjacent complete strings are connected with a main bus through the same branch bus, compared with the prior art, three branch buses are saved for a position between two adjacent complete strings, and the length of the main bus reserved for the three branch buses is saved. For a GIS power distribution device of an ultra-high voltage transformer substation, which comprises multiple complete strings in linear arrangement, the number of the branch buses and the length of the main bus which can be saved by the circuit layout structure provided by the invention are quite considerable, so that the floor area and the equipment cost of the GIS power distribution device are reduced.