This study presents four analysis at unit 4 Kamojang geothermal power plant are exergy analysis at current condition, exergy efficiency optimization, economic optimization, and exergoeconomic optimization with wellhead valve pressure as a variable. Calculations are conducted by using the MATLAB. Thermodynamics characteristic of geothermal fluid assumed as water characteristic which get from REFPROP. Wellhead pressure operational condition 10 bar has exergy efficiency 31.91%. Exergy efficiency optimization has wellhead valve pressure 5.06 bar, exergy efficiency 47.3%, and system cost US$ 3,957,100. Economic optimization has well pressure 11 bar, exergy efficiency 22.13%, and system cost US$ 2,242,200. Exergoeconomic optimization has 15 optimum condition. Exergoeconomic optimization aims to analyze the optimum wellhead valve pressure for maximum exergy efficiency and minimum cost of power plant system.