We synthesize CdTe quantum dots in aqueous solution and characterize the stability of quantum dots in different culture media and different pH environments. The impact of quantum dots on HeLa cellular proliferation inhibition rate is studied. The quantum dots conjugated with transferrin are used for HeLa cell labelling. Finally, the quantum dots are conjugated with dextran and applied in the transparent dorsal skin fold window chamber to observe the dynamics of the bioconjugations in blood vessels. The experimental results show that the quantum dots peaking at 660 nm are stable in cell culture media of DMEM and M1640. When the pH of the buffer solutions increases from 5 to 13, the fluorescence intensity of CdTe increases firstly and then reduces. The cell viability is higher than 80% even when the concentration of quantum dots is 13 μg/mL. The quantum dots conjugated with transferrin obviously target to the HeLa cells. What′s more, the clear dynamic flourescence images of quantum dots conjugated with dextran are observed under microscope. The study shows that such quantum dots can be used for living imaging research successfully.