Heat pipe is an effective device for heat transferring. Using nanofluid as working fluid can significantly increase heat pipe thermal performance. But rate of the performance improvement, is dependent on parameters of the suspended nanoparticles in nanofluid. In this article, for the first time by considering nanoparticle volume fractions and diameters as design variables and the difference between the wall temperature of evaporator and condenser and liquid pressure drop as objective functions, the heat pipe performance has optimized. The used heat pipe is a cylindrical heat pipe with nanofluid as working fluid. Heat pipe thermal performance while using nanofluid has modeled by CFD method and then GEvoM has used to relate between design variables and objective functions. Using the modified NSGAII approach, pareto front has plotted and the values of recommended optimum points has obtained by mapping method. Recommended design points unveil interesting and important optimal design principles that would not have been obtained without the use of a multi-objective optimization approach.