Abstract: Owing to their superior homogenization characteristics, Double-Double (D-D) composite laminates offer an effective approach for the lightweight design of variable-thickness structures. To achieve optimal dynamic performance in composite laminates, a dynamic optimization method for variable-thickness D-D laminates based on the parametric level set method (PLSM) is proposed. Specifically, compactly supported radial basis functions (CSRBFs) are utilized to construct the level set function, ensuring inherent C²-continuity and effectively suppressing numerical oscillations. In this framework, the isolines of the level set function are employed to implicitly describe ply boundaries with clear geometric regularity. By leveraging the homogenization characteristics of D-D laminates, an equivalent dynamic model is established based on the first-order shear deformation theory (FSDT). This modeling approach allows the discrete number of plies to be relaxed into a continuous design variable, thereby enabling the application of efficient gradient-based optimization algorithms, such as the method of moving asymptotes (MMA), to solve the dynamic optimization problem. Furthermore, to ensure manufacturing feasibility and structural integrity, tapering constraints are rigorously integrated into the optimization process. By constraining the gradient norm of the level set function, the local thickness variation rate is effectively controlled, resulting in a continuous gradation in the thickness distribution. Numerical examples involving various boundary conditions demonstrate that the proposed method exhibits excellent robustness. The results indicate that the method can directly take the integral of dynamic compliance over a target frequency band as the objective, driving the thickness distribution to evolve adaptively. Depending on the excitation characteristics, the optimizer adaptively adopts different strategies, such as retaining sufficient thickness to provide bending stiffness under low-frequency loads or shifting the fundamental natural frequency to avoid resonance regions under high-frequency excitations. Consequently, the optimized designs feature clear ply boundaries and continuously tapered thickness distributions. This approach not only significantly suppresses the dynamic response within the target frequency band but also effectively mitigates the stress concentration issues typically encountered in variable-thickness laminate designs.