ABSTRAK Analisis Eksergi pada pembangkit listrik tenaga uap perlu dilakukan untuk menganalisis Eksergi serta memberikan informasi untuk meningkatkan nilai efisien pada Air Heater. Penelitian dilakukan dilab Enegi Program Studi Teknik Mesin Universitas Ibn Khaldun Bogor. Alat yang digunakan yaitu : preassure gauge, preassure transmiter, pompa, Gas analyzer, Solenoid valve, Expantion joint, Expantion joint, Computer personal. Dan bahan : Tube Sheet, Tube, Deeflacting, Baffle, Hopper. Analisa Eksergi Air Heater yaitu menghitung nilai Hot Steam dan Cold Steam, dilanjut dengan menentukan nilai Availability Exergy, Availability Work dan Eksergi loss. untuk mengetahhui nilai Eksergi loss yaitu dengan menjumlahkan terlebih dahulu dari nilai yang sudah dihitung yaitu,  nilai Availability Exergy dan Availability Work. Setelah mengetahui nilai dari Availability Exergy, Availability Work dan Eksergi loss maka dapat menentukan nilai efisiensi. Nilai keluaran dan masukan pada Air Heater Hot Stream sebesar 662,86 kJ/kg, Cold Stream sebesar 568,48 kJ/kg, Availability Exergy sebesar 101582,96 KW, Availability Work  sebesar 44345,33 KW, vailability Work  sebesar 47927,38 KW, Eksergi loss sebesar  KW. Dan efisiensi yang didapat yaitu sebesar 79%. Kata kunci :  Air Heater; analisis eksergi; efisiensi ABSTRACT Exergy analysis in steam power plants needs to be done to analyze the exergy and provide information to increase the efficient value of the air heater. The research was conducted in the Enegi Lab in the Mechanical Engineering Study Program at the University of Ibn Khaldun Bogor. The tools used are : preassure gauge, preassure transmiter, pompa, Gas analyzer, Solenoid valve, Expantion joint, Expantion joint sealing, Computer personal. Dan bahan : Tube Sheet, Tube, Deeflacting, Baffle, Hopper. Air Heater Exergy Analysis is calculating the value of Hot Steam and Cold Steam, followed by determining the value of Availability Exergy, Availability Work and Exergy loss. To find out the value of exergy loss, that is by adding up in advance the calculated value, namely the availability of Exergy and Availability Work. After knowing the value of Availability Exergy, Availability Work and Exergy loss, it can determine the value of efficiency. Output and input values at Hot Stream Air Heater of 662.86 kJ / kg, Cold Stream of 568.48 kJ / kg, Availability Exergy of 101582,96 KW, Availability Work  of 44345,33 KW, vailability Work  of 47927,38 KW, Exergy loss of 9310.25 KW. And the efficiency obtained is 79%. Keywords : Air Heater; exergy analysis; efficiency.