T The industrial revolution causes a person to be able to compete with the changes that occur. Therefore, hard skills and soft skills are needed for graduates with electrical engineering majors to be able to adapt quickly in the field of work related to transmission system design. This final project is a means to be able to increase knowledge and as guidance in the process of preparing planning documents, especially in the electric power transmission system. The purpose of the study is dedicated so that readers can understand the calculation of the planning of conductors, insulators and sagging on the 150kV Overhead Line in accordance with applicable standards. This research can be used as a means for readers to understand the preparation process before the installation of the 150kV Overhead Line is carried out and compile planning documents. The method used is literature study and data collection from existing research. The data collection process itself is obtained from contractors who have the scope of the Engineering Procurement, Construction (EPC) business at the 150kV overhead line . The object of the study was the 150kV overhead line in the Perawang – Tenayan area of Riau Province. The final result of this report is in the form of calculations of the design of the 150kV transmission line using an ACSR type conductor of 250 mm2, the current capacity of 600 A delivers electric power as far as 21.38 km. Using a glass type insulator of 22 units and the value of andongan less than the minimum standard of 10.65 m should be minimun andongan to the ground 11 m, preparation steps before overhead line installation and steps for preparing planning documents.