This article introduces professor Ying Senlin ’s experience in rheumatoid arthritis treatment. Professor Ying considers that “evil,deficiency,toxin,stasis” are the key pathogenesis of rheumatoid arthritis. He puts forward the principle of treatment as building toxin theory and emphasizing on dispelling stasis. In the clinical therapy,he is adept at keeping the compatibility of the cold and the heat,giving attention to both excess and deficiency,focusing on different treatment methods in different periods and using experienced prescriptions and insect drugs flexibly.