This study investigated the accumulation and permeability of active targeted nanoparticles with different sizes in tumor tissues at different stages, and further discussed the impact of changes in key pathophysiological characteristics on the accumulation and permeability of active targeted nanoparticles in tumor tissues. The results showed that the smallest active AuNPs had better accumulation and permeation effects in early tumor tissues with the relatively looser extracellular matrix, larger gaps, lower interstitial fluid pressure, and less receptor expression, which was due to size effects. However, the larger active AuNPs had better accumulation and penetration effects in late tumor tissues with highly expressed target receptors integrin αvβ3 because of the multivalent interactions between larger active nanoparticles and integrin αvβ3. In the midterm, tumor accumulation of active AuNPs was equally influenced by size effects and multivalent interactions. This study will guide a rational design of active targeted nanoparticles for enhancing the diagnosis and treatment of tumors based on their progressions. This work was mainly completed by Ph. D. student Huifang Nie.