Abstract: Acoustic shielding enclosures serve as critical infrastructure for electronic equipment noise testing, requiring multilayer sound-insulating structures to achieve broadband sound insulation performance. To enhance the broadband sound insulation of conventional enclosures, this study optimizes composite structures by analyzing the influence of material stacking sequence and porous material distribution on sound insulation characteristics. The Johnson-Champoux-Allard (JCA) model characterizes the broadband sound absorption of rigid-frame porous materials while inverse acoustic parameter identification of fiberglass is performed using a differential evolution algorithm. A transfer matrix method (TMM) is utilized to construct multilayer composite structures for sound insulation optimization. Results demonstrate that with fixed material composition and total thickness, strategic porous materials layering and distribution effectively enhance sound insulation across frequency bands, enabling broadband noise control. The optimized acoustic enclosure design improves average sound transmission loss by 4.4 dB compared to conventional configurations.