The use of electricity continues to increase every year, which then requires increasing the number of power plants to meet the demand for total electricity usage in the community. Jambi Province has a wealth of natural resources in the form of natural gas, which is quite abundant, making the Gas Power Plant has a very good prospect to fulfill the electricity supply in Jambi. In the written proposal, the power plant is planned to use Siemens SGT-400 as its Turbine Generator, which will be the first to be applied in Indonesia, is believed to be at the heart of this Gas Engine Power Plant Development Plan. In this paper, the Siemens SGT-400 Gas Engine that uses the Brayton cycle is analyzed based on the specifications stated in the proposal and brochure was calculated to find out how the whole system will run in ideal conditions. Inclusion of charts, schematic diagrams, and design layouts will strengthen the analysis performed. The Siemens SGT-400 is concluded that it has a cycle that corresponds to the Brayton Cycle theory which isentropic line is slightly different from theory and has an efficiency of 37%.