Wide-speed-range hypersonic vehicle， as a new strategic high ground in the aerospace field， face the challenge of balancing subsonic aerodynamic performance with transonic and supersonic as well as hypersonic characteristics due to the maximization of their flight speed and altitude range. To alleviate the high and low speed aerodynamic design conflict， this paper combines a global optimization approach based on surrogate models with a local optimization approach based on adjoint gradients to perform a multi-objective stepwise optimization of the layout parameters and airfoil shapes of the wide-speed-range configuration， spanning from the global to the local scale. The results indicate that under the constraints on subsonic lift coefficient and hypersonic drag coefficient， the layout parameter optimization method based on surrogate models can enhance the subsonic lift-to-drag ratio by 9.5%， while maintaining hypersonic aerodynamic performance. Furthermore， by selecting the configuration on the Pareto front of layout parameter optimization results with the optimal subsonic aerodynamic characteristics， a gradient optimization of the wing profile is performed using an adjoint gradient-based method. The optimization results demonstrate that the gradient optimization effectively enhances the drag characteristics during subsonic and hypersonic cruising states， leading to the geometric optimization of the airfoil as a dual-S shape that balances subsonic and hypersonic aerodynamic characteristics. Through the aforementioned optimization from layout parameters to profile parameters， the subsonic lift-to-drag ratio of the waverider-wing configuration increased by 12.4% compared to the original configuration， while the hypersonic lift-to-drag ratio improved by 6.2% compared to the original configuration.