This review paper presents an overview of simulation-based hydrodynamic design optimization of ship hull forms. A computational tool that is aimed to accomplishing early-stage simulation-based design in terms of hydrodynamic performance is discussed in detail. The main components of this computational tool consist of a hydrodynamic module, a hull surface modeling module, and an optimization module. The hydrodynamic module includes both design-oriented simple CFD tools and high-fidelity CFD tools. These integrated CFD tools are used for evaluating hydrodynamic performances at different design stages. The hull sur-face modeling module includes various techniques for ship hull surface representation and modification. This module is used to automatically produce hull forms or modify existing hull forms in terms of hydrodynamic performance and design constraints. The optimization module includes various optimization algorithms and surrogate models, which are used to determine optimal designs in terms of given hydrodynamic performance. As an illustration of the computational tool, a Series 60 hull is optimized for reduced drag using three different modification strategies to outline the specific procedure for conducting simulation-based hydrodynamic design of ship hull forms using the present tool. Numerical results show that the present tool is well suited for the hull form design optimization at early design stage because it can produce effective optimal designs within a short period of time.