The modeling optimization of hydraulic shell pipeline for 3D printing should not only meet the function and performance requirements，but also embody the advantages of 3D printing technology.Through the curve and surface algorithm based on NURBS,a set of modeling optimization method suitable for hydraulic shell pipeline is established. The key line is obtained by the method of edge line extraction, and the pipeline routing is designed based on the principle of reducing the flow resistance and energy loss as much as possible.In order to reflect the advantages of 3D printing technology as the goal,to achieve product function and performance as constraints,the hydraulic shell pipeline modeling optimization was carried out,and the fluid simulation analysis was carried out.The results show that：after optimization，the maximum local pressure of Z-shaped pipeline is reduced by 99.8%，the negative pressure area is significantly reduced，and the flow velocity is reduced.The optimized hydraulic shell surface pressure distribution is more uniform，the pressure loss is reduced by 53.2%,and the performance of the shell is significantly improved.