Abstract: OBJECTIVE To investigate the affecting factors of the morphology on the novel rod hydroxycamptothecin (HCPT) nanoparticles. METHODS Choose different drug loading ratio, different preparation methods and the existence of the other stabilizers or not as examination factors to prepare HCPT nanoparticles stabilized by the novel codendrimer PAMAM-co-0.25OEG, PGD, respectively. The morphology under the electron microscope of the nanoparticles was observed. RESULTS The morphology under the electron microscope of HCPT nanoparticles stabilized by codendrimer PGD was not affected by the preparation methods, but was influenced by the ratio of the drugs and stabilizers (drug loading ratio). While the drug loading ratio increased from 4:1 to 1:3, the existence of large amount of stabilizer PGD made it easier to package HCPT drug and form spherical nanoparticles. HCPT nanoparticles of high drug loading ratio stabilized by both PGD and Chol-PEG600 would also form some spherical particles. CONCLUSION The morphology of HCPT nanoparticles are affected by the radio and structure of the stabilizing agent. HCPT nanoparticles with similar particle size can also be with comparatively different Zeta potential according to the characteristics of the stabilizers.