Water soluble CdTe quantum dots have shown potential as a platform for development of live cell imaging, but their cytotoxicity limits their biological applications. To decrease their cytotoxicity, an approach to modify CdTe quantum dots (QDs) with polyamidoamine (PAMAM) was employed by forming covalent bonds between them. The resultant nanocomposites as a cell imaging bioprobe for live PK15 and their in vitro toxicity were also investigated. The results showed that the prepared nanocomposites were able to enter PK15 cells with good biocompatibility and low cellular toxicity.