SKG mouse, as a model of spontaneous rheumatoid arthritis (RA) bred recent years, is similar to the patients with RA. We analyzed the clonotypes of T cell infiltrating into joints of SKG mice in initial stage and late stage of RA by using reverse transcriptase-polymerase chain reaction (RT-PCR) and subsequent single-strand conformation polymorphism (SSCP). The results indicated that the percentages of clonotypes TCR Vbeta2 and Vbeta8.2 of T cell clonotypes increased obviously to 72.3% and 60.2%, respectively. Mice number with identical TCR Vbeta2 and Vbeta8.2 clonotypes also clearly increased in late stage of disease to 100% and 75%, respectively. These results mean that T cells with TCR Vbeta2 and Vbeta8.2 clonotypes probably play an important role in RA progression of SKG mouse. Sequencing of the extracted DNA verified that common bands on SSCP gel were derived from the same T cell clones among samples from different joints. The results we obtained implied that RT-PCR/SSCP method was a sensitive and credible method for analyzing T cell clonotypes. When the T cells of SKG mouse were adoptively transferred to a nude mouse, it was verified that the T cells infiltrating into joints were related to morbid formation of RA.