As a new family of nanomaterials, carbon nanotubes (CNTs) exhibit unique properties such as their capacity to penetrate into the cells and low immunogenicity, which have attracted increasing attention in biomedical field and make their application in drug and gene transfer systems being possible. So getting more information about the interaction of CNTs with biomacromolecules is crucial for further investigation of CNTs in therapeutic applications. The interaction between CNTs and BSA under physiological condition was investigated by fluorescence quenching, synchronous fluorescence and red edge excitation shift (REES)method. The results showed that CNTs could significantly decrease the fluorescence intensity of BSA. While the results of synchronous fluorescence and REES indicated that CNTs almost had no influence on the conformation of BSA. So the authors concluded that the mechanism of interaction between CNTs and BSA was non-specific adsorption.