Nanoparticles have many potential applications in tumor therapy. Systemically administered nanoparticles should remain in circulation for a long time to increase their accumulation in targeted tissues before being cleared by the reticuloendothelial system, and be effectively internalized by the targeted cells, which can be influenced significantly by the physicochemical characteristics of nanoparticles, such as particle size, surface properties, and particle shape. This review highlights the impact of the main affects of physicochemical properties on nanoparticle transport behavior in blood, their uptake and clearance by macrophages and their consequent biodistribution, as well as their interaction with targeted cells.