Abstract: Recurrent aphthous ulcer（RAU） is a common disease, Two hundred and thirty-one patients with RAU were treated with Centipede agents, with total efficiency of 89.2%. In order to investigate the mechanisms of the therapy, the related immune indexes were studied before and after treatment in 40 patients. The results showed that both the serum IgG and the appearance rate of the E-rosette were increased than the pretreatment levels （P＜0.01）. The serum IgG was significantly decreased. But the sialic Igm was significantly reduced only offer treatment. The results indicat that the Centipede agents have an effect of adjusting general immune state.