This study introduces a comprehensive computational framework for graded multiscale topology optimization (MTO) that integrates periodic boundary conditions (PBCs), localized homogenization, and inter-subdomain coupling to enable advanced structural design. The design domain is partitioned into multiple independent yet interactively coupled subregions, each optimized to host distinct, spatially-tailored microstructures characterized by homogenized elasticity tensors. A tunable coupling parameter wc​ is incorporated to control stiffness continuity across subdomain interfaces, ensuring mechanical coherence throughout the structure. To address practical fabrication constraints, a projection-based filtering scheme is implemented, enhancing manufacturability without compromising structural performance. Numerical results validate the framework’s superiority over conventional SIMP and de-homogenization techniques, exhibiting marked enhancements in compliance reduction, material utilization, and stress uniformity.