The invention provides a medicinal composition for treating rheumatoid arthritis. The medicinal composition for treating the rheumatoid arthritis is prepared from the following raw materials in part by weight: 1 to 2 parts of common monkshood mother root total alkali and 1 to 3 parts of white paeony root polysaccharides. The invention also provides a preparation method and application of the medicinal composition. The medicinal composition for treating the rheumatoid arthritis has the advantages of definite pharmacological effect, inflammation resistance, pain remission, good effect of treating the rheumatoid arthritis, optimum pharmacological compatibility and high quality controllability, and is a new clinical choice.