With regard to the increasing use of satellites platform in the geostationary orbit, a system engineering tool, FADSat, has been developed to reduce the prohibitive cost and time of their conceptual design phase. The proposed tool effectively conducts the design of the geostationary Earth orbit satellite platform lying in the mass range of 1–7000 kg. The main feature of the FADSat is to determine the conceptual design of the satellite platform with both high time performance and acceptable accuracy. Using this tool, one can readily extract the characteristics of the structure, attitude determination and control, command and data handling, electrical power, and other subsystems of a satellite. The FADSat exploits a statistical design model in the first instance to yield a rough estimation of the satellite design, i.e. a rapid extraction of the budgets for mass, power, and dimensions of the satellite subsystems as well as the cost of the satellite. Then, using a parametric design model approach, it performs subsystems design more accurately and ascertains their component specifications in terms of a catalog of products with corresponding manufacturers. A database of 462 geostationary Earth orbit communication satellites (with 30 different geostationary Earth orbit satellites platforms (launched from 2000 to 2017 has been used in this paper to implement the statistical design model approach. This tool developed in the LabVIEW software is capable of contributing to the satellite production phases as a connection to the hardware simulators of different subsystems. Herein, after describing the general concepts utilized in the satellite design, we have introduced various parts and relations of the FADSat tool. The tool’s accuracy was amply verified through flight prototypes, indicating an average error of 15% in the obtained results.