Orchards in granite red soil region of South China are generally faced with serious soil and water loss.Grass planting under forest can effectively reduce runoff and sediment yield and soil and water loss of orchards.Taking Tangbei small watershed in Xingguo county of Jiangxi province as the research area,this paper studies the runoff and sediment characteristics of orchards with different grass growing measures under natural rainfall by setting five orchard runoff plots with different grass growing measures.The results showed that：（1）the runoff and sediment yield of orchards with different grass planting measures were significantly different,and increased with the increase of rainfall and rainfall erosivity；（2）compared with navel orange+Artemisia argyi,navel orange+purslane,navel orange+Melilotus and navel orange clear tillage,the runoff and sediment yield of navel orange+white clover decreased by 54.09%,53.15%,58.07%,69.85%,61.53%,59.94%,68.88%,87.26%,respectively,which had good effect of reducing runoff and sediment；（3）different grass planting measures had a certain effect on the grain size composition of orchard erosion sediment,but the difference was not obvious.Among them,the average content of sand is the least,and the average content of clay is the most.Therefore,grass mulching can effectively reduce soil and water loss under orchard forest in red soil region with granite in Southern China.