By comparitive study on Fe and Mn content of ginseng roots and the enviroments betweer healthy and infected plants. It was concluded that the red skin disease of ginseng was caused by pre cipitation of Fe and Mn on roots in the process of soil lessivation under the influence of fluctuation of redox in periodically over-wet condition of lessive soil. The main point of prevention should be to drain and aerate the over-wetted soil. A scheme for draining ginseng growing-bed soil was proposed.