The invention provides a power system diagram drawing method based on a power supply radiation range. based on the integrated GIS platform model data, automatic drawing of the power supply system diagram is realized; the target transformer substation is placed in the center of the drawing; and all outgoing line switches in the transformer substation are tracked and analyzed, classification is carried out according to the type of the line looped network, the single-radiation line without the looped network is placed on the left upper portion of the drawing, the single-radiation line and the inner looped line of the target transformer substation looped network are placed on the right upper portion of the drawing, and the single-radiation line and outer looped lines of other transformer substation looped networks are evenly placed below the drawing. According to the invention, the expenditure of human resource cost and the probability of manual errors are reduced; Intelligentization of the mapping work is improved, timely and correct generation and updating of the drawing are ensured; Meanwhile, the drawn system diagram drawing can visually display the ring network connection condition and the ring network distribution proportion between all outgoing line switches in the transformer substation and other transformer substations, a distribution network manager can immediately determine the feeder line where the related load is located, and a load transfer plan and an on-site load control scheme are analyzed and decided.