To effectively mitigate the combined impulsive and fragmentary loads exerted by near-field explosion， a multi-layer composite protective structure has been developed， incorporating an anti-penetration layer， a coordinated support layer， and a cushioning energy-absorption layer. A finite element analysis model was established and validated through near-field explosion experiment. Utilizing the outcomes of finite element simulations， a response surface approximation model for the composite protective structure was constructed. With the areal density and overall thickness of the composite protective structure as the optimization targets， a multi-objective optimization of the thickness distribution was conducted under the individual and combined effects of fragments and shock waves using the Non-dominated Sorting Genetic Algorithm II （NSGA-II）. And the Pareto optimal solution set was obtained. The findings demonstrate that， in comparison to the initial design， the areal density of the optimized composite protective structure subjected to the individual action of fragments can be decreased by up to 19.2%， with a maximum thickness reduction of 10.0%. Under the individual action of shock waves， the areal density can be reduced by up to 34.9%， and the thickness by up to 27.5%. Under the combined action of shock waves and fragments， the areal density can be reduced by up to 19.2%， and the thickness by up to 10.0%. For application scenarios where the thickness is constrained to no more than 40 mm， the optimized composite protective structure exhibits an approximately 17.5% reduction in areal density and a 9.1% reduction in total thickness compared to the initial design. It was noted that the Pareto optimal solution sets obtained from the individual fragment action and the combined action are nearly identical， indicating that the composite protective structure significantly diminishes the influence of shock waves on the subsequent fragment impact， thereby effectively mitigating the combined effects of shock waves and fragments.