Abstract: Objective :To investigate the antitumor effect of hydroxycamptothecin (HCPT) loadednanosphere made from poly(ethylene glycol)-poly (-benzyl-L-glutamate)(PEG-PBLG) in the treatmentof oral squamous cell carcinoma or colon cancer. Methods :HCPT/PEG-PBLG nanosphere was pre-pared by the diafitration method. Transmission electron microscope (TEM) was used to observe theshape of nanosphere. Xenografts of oral squamous cell carcinoma (Tca8113 cell line) or colon cancer(Lovo cell line) implanted in BALB/c nude mice were treated with HCPT/PEG-PBLG nanosphere. Thegrowth state and histopathological changes of Tca8113 cells xenografts or Lovo cells xenografts were ob-served and the tumor doubling times and inhibition rate were calculated. Results :The shape of HCPT/PEG-PBLG nanosphere was a core-shell structure and the nanosphere size was about 230 nm, with200 nm in core diameter and 30 nm in shell thickness. Compared with the control group, Tca8113 cellsxenografts or Lovo cells xenografts in all HCPT-treated group grew slowly and tumor doubling timesprolonged(P<0.01).The tumor inhibition rate of HCPT/PEG-PBLG nanosphere treated group was signif-icant higher than that of HCPT treated group (P<0.01). There was no any tumor inhibition effect ofPEG-PBLG treated group(P>0.05). The xenografts inhibition rate for oral squamous cell carcinoma was69.6% (HCPT 3mg/kg/qd)、74.1% (HCPT 10 mg/kg/qd)、59.8% (HCPT 3 mg/kg/qod) and 85.6%(HCPT/PEG-PBLG 3 mg/kg/qod), respectively. The xenografts inhibition rate for colon cancer was70.0% (HCPT 3mg/kg/qod) and 83.8% (HCPT/PEG-PBLG 3 mg/kg/qod). The histopathology showedthat there were many phagosomes inside tumor cells in PEG-PBLG or HCPT/PEG-PBLG treated group,but there was no phagosome inside tumor cells in HCPT treated group under TEM. There were manyapoptotic cells and necrotic area in HCPT or HCPT/PEG-PBLG treated group. Conclusion : HCPT/PEG-PBLG nanosphere could enhance the antitumor effect of HCPT and PEG-PBLG nanosphere wouldbe an ideal vector for drug analogous to HCPT.