In present calculation of electric distance for overhead transmission line, the accuracy is low and the calculation efficiency cannot meet the design requirement. Therefore, three-dimensional calibration system of electric distance for overhead transmission line is developed based on catenary calculation method, space coordinate transform and OpenGL library. In the system, the three-dimensional electric distance calibration is implemented between phases on the same and different circuit in transmission lines with single-, double-and multi-circuit on the same tower. In addition, three-dimensional models and dynamic interactive of tower, insulator and catenary are displayed. The swing angle of insulator and tension of catenary can be automatically calculated under different design conditions. The system is very practical in improving the efficiency and reducing labor intensity of designer, and provides technical references for path selection, layout and locating calibration of towers in transmission lines.