It was satisfactory using the ethyl acetate extract of Tripterygium wilfordii (TW) to treat rheumatoid arthritis (RA). The results showed that the ethyl acetate extract of TW was the effective component part of TW. Although the therapeutic effect of 15 cases with RA cured by triptolide was as effective as the ethyl acetate extract of TW, triptolide could impair some patients' hearts. This suggested that triptolide was one of the main effective elements of TW, but it was also one of the main toxic elements. Clinical research indicated that: (1) the effect of TW in treating RA was the synergistic action of elements with triptolide as the main; (2) triptolide may act as a major standard of controlling the quality of the preparation of TW and assure clinical use safely.