The boiler efficiency is improved with the help of economizer it is one of the main accessory part in the boiler. Boiler feed water is preheated with the entry of reused flue gas through economizer. This present work is planned to analyze the overall heat flux and overall heat transfer in the boiler economizer. Higher amount of flue gases passing around the economizer to preheat the feed water at the same time much more heat is transferred. The heat transfer is analyzed by statistical method with influence of different process parameters. Economizer fin dimensions are major consideration to taken for this analysis and estimate the overall heat flux and overall heat transfer. The process parameters of this study are named as thickness of the fin (3.5 mm, 4 mm, 4.5 mm and 5 mm), Height of the fin (4 mm, 5 mm, 6 mm and 7 mm), Fin gap (12 mm, 14 mm, 16 mm and 18 mm and Tube diameter (44 mm, 46 mm, 48 mm and 50 mm). The response values are finding as overall heat flux and overall heat transfer.