The invention discloses a generation method for a logic geographic diagram of a power transmission network. According to the method, geographic locations of sites are referred on the basis of a global model of the power transmission network, and the generation of the high-density logic geographic tidal current diagram of the power transmission network is realized by a subarea mode and a constraint algorithm; the method comprises the following steps of dividing a plant-station object in the model of the power transmission network into a plurality of subareas according affiliated subarea information; performing statistics on the number of plant-stations contained in the subareas, wherein the smallest elliptical area contains the plant-stations; automatically working out the width diameter, the height diameter and the rotation angle of an ellipse; computing a longitude and latitude mean value of the plant-stations in the subareas, wherein the longitude and latitude mean value serves as barycentric coordinates; acquiring a system diagram of the subareas of the power transmission network and inflection point locations of connecting lines among different areas by a compression method; maintaining the minimum interval constraint of the sites in the subareas, and receiving bidirectional self-adaption correction after the site locations is manually modified or the shape of the ellipse is modified to finally form the high-density logic geographic tidal current diagram, and therefore the foundation is laid for the scheduling operation decision-making of the power transmission network.