Raman spectrum and surface enhanced Raman scattering (SERS) spectrum of the nude mouse serum are measured using laser Raman confocal micro-spectrometry. The results show that the Au nanoparticles active substrate can enhance the Raman spectra dramatically. A lot of information which conventional Raman spectroscopy fails to detect emerges. This is due to the chemical adsorption and interactions between the gold nanoparticles and the substances in serum. The information is important for the analysis of the most components and structures of the serum proteins. With SERS spectrum, even micro-sample can also reflect the molecular structure information of the serum proteins, lipids, carbohydrates, ribonucleic acid and other components. Information of the serum components can reflect physiological and pathological metabolism changes of the cells and tissues in the body. So SERS spectrum of the serum would provide an effective means for the diagnosis and therapy of diseases.