Abstarct: In recent years, with the consumption growth of natural gas in Iran, the number of pressure drop stations has increased significantly. In the throttling valves of these stations, the temperature drop due to the Joule-Thomson effect causes the gas to hydrate, freeze the valves, and block the transmission path. Hence, about 14,000 Indirect Fired Water-Bath Heaters (IFWBH) have a duty for preheating the high-pressure gas before entering these valves. In this article, intending to optimization and compromising between maximum efficiency and minimum losses and cost, IFWBHs were modeled thermodynamically and thermo-economically, three objective functions including thermal efficiency, entropy generation number and wasted cost number are defined and the mathematical model was proposed in two scenarios. Then the model was solved baxsed on one of the mexta-heuristic algorithm techniques known as the multi-objective genetic algorithm namely Non-dominated Sorting Genetic Algorithm, using the entropy generation minimization method, by simultaneously running the EES and MATLAB softwares and the Pareto optimal fronts of the scenarios were determined. The results of the implementation of the model presented in the form of relationships, curves and dimensionless groups, compared to the results of a real sample, indicate its acceptable performance and can be used as a suitable reference for the optimal design of IFWBHs. baxsed on the results, improving the performance of these heaters only within a certain range of thermal efficiency has a techno-economic justification, and the total annual cost and required heat capacity in the range of 10,000 to 100,000 SCMH of passing natural gas volumetric flow rate depends on the targeted thermal efficiency in addition to the volumetric flow rate. Meanwhile, for flow rates less than the lower limit of this range, for each one percent increase in thermal efficiency, we can expect to save about 10,000 € in the total annual cost and 250 kW in burner heat capacity. On the other hand, for flow rates higher than the upper limit of this range, the effect of the two mentioned parameters in improving the thermal efficiency of IFWBHs is almost negligible.