<p>The aerodynamic profile of large-scale wind turbine blade exerts critical influences on energy conversion efficiency and structural integrity. Key parameters including chord length and twist angle distributions constitute a high-dimensional design space. Under regular conditions, these parameters can be optimized under smoothness constraints to improve optimization efficiency. However, minor protrusions or concave features on the blade surface under quasi-smoothness constraints may further improve aero-structural performance. This study proposes a constrained parametric optimization framework that incorporates quasi-smoothness constraints to enhance aero-structural performance, comprising three principal components: Through smoothness evaluation criteria for chord length and twist angle distributions, establishing a parametric model with quasi-smoothness constraints and corresponding parameter mapping relationships. Implementation of computational fluid dynamics and finite element analysis to evaluate aero-structural performance sensitivity, revealing that 3% parametric deviations induce approximately 10% comprehensive variations in aero-structural characteristics. Through multidisciplinary optimization maintaining quasi-smoothness constraints, ensuring the variation range of the variables is within 3%, the implemented aero-structural enhancement strategy achieves up to 3.89% output torque augmentation coupled with 2.74% improvement in structural resistance to deformation performance. This study substantiates that strategic local geometric perturbations within quasi-smoothness constraints can effectively improve blade aero-structural performance metrics.</p>