As the precursor material inherently determines the fundamental structure of hard carbons, a direct manipulation of precursors at the molecular level promises enhanced flexibility in designing hard carbon architectures, which plays a pivotal role in dictating the final microstructural properties and, ultimately, the overall sodium storage performance. In this study, we present a novel generalized strategy utilizing P and O double cross-linking to convert pitch into a thermosetting precursor, creating copious micropores within pitch-based carbon. These micropores serve as essential pathways and active binding sites for sodium ion transport and storage, leading to pitch-derived hard carbons with a remarkable specific capacity of 416.1 mAh/g and an impressive initial Coulombic efficiency of 89.7%. Extensive study revealed a strong correlation between the increased plateau capacity and the closed pore volume, validating the micropore-driven sodium ion storage mechanism. Our findings underscores the groundbreaking significance of cross-linking in precursor modification, paving the way for the design and synthesis of high-performance hard carbon anodes for next-generation Na-ion batteries.