The medicine for treating rheumatoid arthritis is prepared with mulberry twig, angelica, ledebouriella root and Sichuan achyranthes root in certain weight proportion, and through separate washing the materials, crushing, setting in extracting pot and adding water in 8-16 times, boiling for 0.8-1.2 hr, 200-mesh sieving to obtain filtrate, decompression concentrating to density of 1.05-1.08, 120-mesh sieving; repeating the above said process for twice; merging the filtrate of three times and spray drying to obtain the extracts of the materials; 60-mesh sieving, mixing the extracts and encapsulating to obtain medicine capsule. The medicine is suitable for preventing and treating rheumatoid arthritis.