In nature and engineering applications, air/hydrofoils possess a vast array of shapes which are suited to the flow regimes in which the foils typically operate. Recently study on the effects of foil shape on “steady” drag, propulsive efficiency [1] and propulsion speed [2] in unsteady hydrodynamic propulsion indicate that changing the foil shape while fixing the heaving-pitching kinematics and flow conditions, could impact the propulsive efficiency significantly. Several methods are available for defining an arbitrary airfoil. However, for optimization some methods are better suited than others because they can approximate the real airfoil shape using a minimal number of design variables and computations can be faster. Using this as our motivation, we used two well-known geometric parameterization methods, the singular-value decomposition (SVD) method and class-shape transformation (CST) method, and a gradient-based optimization scheme to design the foil shape and improve the propulsive efficiency of the unsteady propulsors. Both parameterization methods yield a foil shape with a thick forebody and tapered trailing edge, of which the efficiency exceeds the NACA0012 foil by about 22%. The results show that, CST method performs better in presenting physical foil while SVD method is better at revealing more foil shape details, which is probably related to its higher efficiency in recovering foils with fewer design variables.