The Kunming mice immatured oocytes in vitro maturation culture system are established to investigate the reproductive toxicity of CdSe/CdS/ZnS quantum dots (QDs). QDs stock solution is added into oocyte culture medium at a final concentration of 28.90 nmol/L. Then, QDs and oocytes are co-cultured at 37 ℃, 5% CO2 for 4, 8 and 20 h, respectively. The morphological information of oocytes are observed and analyzed under phase-contrast fluorescence microscope. The results demonstrate that QDs enter cumulus cells and accumulate with co-culture time. QDs can not penetrate oocytes zona pellucida, which is confirmed by laser scanning confocal microscope with high spatial resolution. After being treated for 20 h and being rejected by oocytes, QDs decrease the ratio of oocyte in vitro maturation dramatically.