Leukemia, unlike solid tumors, has no definite shape and spreads throughout the whole circulatory system, therefore the therapy of leukemia requires medication to stay longer in the circulatory system. Anisotropic nanoparticles, showing longer blood circulating life than that of isotropic nanoparticles reported in previous research, meet the demands of leukemia therapy. Based on this strategy, superparamagnetic anisotropic nano-assemblies (SANs) were fabricated and loaded with vincristine (VCR) to form VCR-SANs. When compared to the same dose of VCR-loaded isotropic nano-assemblies (SINs), the decrease in the leukocytes count and the positive expression ratio of CD13 in the VCR-SANs group were 19.38% and 16.4%, respectively, which indicated the improved anti-leukemia activity of the VCR-SANs. From the results of the pharmacokinetics study, the VCR-SANs remarkably held the amount of drug removed from the whole body per unit time half of the isotropic group and the concentration of drug in blood plasma against time was 2.1 times the isotropic group, demonstrating the rapid and sustained release behavior and longer blood circulation when combined with the results of in vivo tissue distribution studies. In summary, anisotropic nano-assemblies were found to be more promising than isotropic nano-assemblies via our in vivo and in vitro examinations.