The aim of this work is to investigate the performance of boiler of power plant in Tello Makassar. The boiler generated an electricity power of 50MW to fulfil the electricity needed of people in Makassar city. Performance investigation of the steam generator is very important due to the operation of the boiler is a long time since 1971. The methodology in this study using energy and exergy analysis as well as entropy generation approach. The methodology will be applied in all boiler components namely; Combustion Chamber, evaporator, superheater IA, superheater IB, superheater II, air heater I, economizer and air heater II. The result shows a significant decrease in efficiency of energy and exergy for superheater II of 28.98% and 21.28% respectively. The performance of superheater I and air heater II shows energy efficiency above 90%, while the exergy efficiency are less than 50% for both of components. The economizer were in the middle performance by placed the efficiency of energy and exergy in 64.48% and 48.35% respectively. In general, boiler components are working very well by reach energy efficiency of 90% in average. However, by applications the exergy analysis the performances of the components does not touch of 50%. The result of the study also shows the energy and exergy efficiency of boiler are 41.96% and 29.36% respectively. Meanwhile, the heat that is inducted to the steam turbine are 35.98MW and 15.12MW by energy and exergy analysis when the plant was working on 10.3MW of a load.