To extend cable-stayed utility longevity and reduce the frequency of vortex-induced vibration. Firstly, this paper designs a new-style cross-section shape of the stay-cables' casing with the help of aerodynamics. Secondly, it establishes its expression making use of CFD, afterward, it compares the new model with existing and gets the new modle can avoid coming into being significantly vibration. It assures the security of cable stayed Bridge. Lastly, it optimizes cross-section shape basing on Genetic Algorithms and obtains the best model.