High temperature heat exchanger technology is important with respect to improving the performance of power and propulsion system. This study proposes and optimizes a new heat exchanger tube shape by reducing the size of the tube bundle and improving structural characteristics such as the thermal stress and resonance. Various tube shapes were proposed and a FE analysis was performed to select the tube with the best structural characteristics. The response surface methodology was employed to establish mathematical approximation models using the results of design of experiments as a function of the geometric parameters of the selected tube. Also, the main effects of various geometric parameters on the selected tube were investigated. The geometric parameters such as offset length, the straight distance between one end and the other end of the tube, the tube length in a straight portion and fillet radius were assessed. The geometric parameters of the selected tube were optimized using the RSM and multi-objective genetic algorithm. We suggested the calculated coefficients of the regression equation for the objective function, optimized data, and an optimization procedure of the tube. The presented findings could be used in the preliminary design of the heat exchanger used in high temperature.