Objective We synthesized novel magnetic pirarubicin nanoparticles for targeted intravesical chemotherapy to treat bladder cancer. Methods Pirarubicin was grafted on Fe3O4 nanoparticles which were surface-functionalized with amino-groups via N,N′-Carbonyldiimidazoleas targeted intravesical infusion chemotherapy agents. Mimetic position in vitro by external magnetic field and inhibition to bladder cancer cells of prepared agents were demonstrated. Results Pirarubicin was successfully grafted on magnetic Fe3O4 nanoparticles whose size were around 40nm. The residual of pirarubicin on the pharmaceutic agents was above 90% in buffer solutions of various pH. They also could be positioned to certain area by external magnetic. Meanwhile, the prepared magnetic pirarubicin nanoparticles gave multiple-inhibition to bladder cancer cells by THP and Fe3O4. The inhibition rate was up to 58.44% after co-cultured for 2h. Conclusions These magnetic pirarubicin nanoparticles have a great potential for clinical use in infusion chemotherapy.