In this paper, a genetic algorithm is applied to an optimization problem of material composition for a hollow circular cylinder of step-formed functionally graded materials. In the first place, the one dimensional transient temperature distribution for a laminated composite hollow circular cylinder is analyzed theoretically. Furthermore, making use of Airy's stress function method, the thermal stress components are formulated under the mechanical condition of being traction free. As a numerical example, the hollow circular cylinder composed of zirconium oxide and titanium alloy is considered. And, as the optimization problem of minimizing the thermal stress distribution, the numerical calculations are carried out making use of genetic algorithm without supposing a distribution function of material composition, and the optimum material composition of each layer is determined taking into account the effect of temperature-dependency of material properties.