Abstract: Surface modified gold nanorods which are hexadecyltrimethylammonium bromide (CTAB) stabilized were obtained and their biocompatibility and function of delivering fluorescent molecules into cells were also studied. The CTAB stabilized gold nanorods were surface modified with polyethylene glycol (PEG) through in situ dithiocarbamate formation and ligand exchange. The surface modified gold naorods (PEG-GNRs) with terminal amine on its surface was prepared. The shape and optical properties of surface modified GNRs were characterized by transmission electron microscope (TEM) and UV-Vis. Then, the biocompatibility of PEG-GNRs was measured with MTT assay. A confocal laser scanning microscope (CLSM) and a fluorescence activated cell sorter (FACS) were employed to study PEG-GNRs function of delivering fluorescence molecules into cells. Results show that PEG-GNRs have good compatibility and can be used as a vector for delivering fluorescent molecules or drug into cells for cell imaging in the future.