Surface-enhanced Raman Spectorscopy (SERS) spectra of serum, knee muscles and synovial tissues of normal rats and Model of Knee Osteoarthritis (KOA) are analyzed, providing an experimental basis for biological changes of KOA. Twenty normal healthy male SD rats were raised under the same conditions and randomly divided into normal control group (referred to as “normal group”) and KOA model group (referred to as “model group”), with 10 rats in each group. The KOA model was prepared by intra-articular injection of 0.03 mol·L-1 of l-cysteine and 4% papain. The classification of surficial enhanced Raman spectra in serum, knee muscle and synovial tissue of rats was detected by silver nanometer substrate fluid. NGLabSpec software was used to compare the differences of Raman frequency shift and characteristic peaks between the two groups, and OriginPro 8.5 software was used to analyze Raman spectra. In the serum, within the range of Raman frequency shift 400～2 000 cm-1, there were 12 characteristic peaks in the normal group and 14 in the model group, and the peak strength of most characteristic peaks in the model group was lower than that in the normal group, and significant difference characteristic peaks appeared in 495, 883 and 1 447 cm-1 of the two groups; in the muscle tissue of the knee joint, there were 12 characteristic peaks in the normal group and 13 in the model group, there were significant differences in the Raman strength of the characteristic peaks of homogeneity between the two groups; in synovial tissues and the normal group has 10 characteristic peaks, has 15 model group, two groups of the common characteristic peak of peak intensity change is not obvious, but in the 655, 950, 1 335, 1 447 cm-1 of the homogeneous characteristic peaks show that the peak strength of significant differences, in 655 and 950 cm-1 of a significant rise in the model group, and 1 335 and 1 447 cm-1 model is the relative strength of two groups decreased significantly. KOA model led to a significant decrease in the number of homogenous characteristic peaks of serum, knee muscle and synovial tissue, and an increase in different substances. Thus the metabolic balance of substances was seriously broken. SERS is a fast and accurate detection method, which can be used for the detection of KOA model.