The invention relates to a functional area power distribution network refined planning method which is characterized by comprising the following steps: (1) confirming a capacity, a location and a power supply range of a high voltage transformer substation by means of collecting a functional area power grid network frame, a load and data of development needs; (2) conducting functional area high voltage power distribution network planning; (3) and conducting functional area medium voltage power distribution network refined planning. The functional area medium voltage power distribution network refined planning comprises the following steps: (1) establishing a typical interconnection structure of a small-scale high-voltage transformer substation; (2) building a functional area power grid transformer substation interconnected structure combined with a high voltage substation location and a power supply range; (3) building a functional area power grid medium voltage network frame scheme; (4) calculating a medium voltage feeder contact situation, and giving the wiring of medium voltage network frame. The functional area power distribution network refined planning method has the advantages of being reasonable in design, high in reliability, capable of saving construction costs, convenient to maintain and the like. In addition, according to the functional area power distribution network refined planning method; scientific evidence is provided for functional area power distribution network refined planning.