Nanoprodrugs that are directly assembled by prodrugs attract considerable attention with high anticancer potentials. However, their stability and efficiency of tumor-targeted delivery remain a major challenge in practical biomedical applications. Here, we report a new deep tumor-penetrating nano-delivery strategy to achieve enhanced anti-cancer performance by systematic optimization of a porphyrin-doxorubicin-based nanoprodrug using various PEGylations/crosslinks and co-administration of targeting peptide iRGD. Polyethylene glycols (PEGs) with different molecular weights and grafts are employed to crosslink the nanoprodrug and optimize size, charge, tumor accumulation and penetration, and anti-cancer efficiency, etc. The tumor penetration was validated in syngeneic oral cancer mouse models, patient-derived xenograft (PDX) models, and oral cancer tissue from patients. The optimized nanoprodrug co-administrated with iRGD remarkably enhances the accumulation and penetration both in tumor vascular and PDX tumor tissue. It is effective and safe to improve in vivo therapeutic efficacy via the passive tumor targeting dependent and independent mode. Our tumor-penetrating nano-delivery strategy is promising to strengthen the nanoprodrugs in clinical implementation.