Abstract: The vegetation features and biomass of sandy rangeland in semi-arid area of Yanchi County,Ningxia were studied by means of plot investigation methods since 1991.Three treatments were respectively old closed land,new closed land and contrast land of different periods.The results showed that community composition had varied regularly after enclosure and the plant diversity of the grassland community had increased as the enclosing time extended;The vegetation coverage,mean height and biomass in the three areas have no significant differences.The community in old enclosed land was dominated by perennials;In the view of palatability of plant composition,community of new enclosed has higher palatability than old enclosed,which proves partly that long-term enclosure can not increase grazing values for rangeland in semi-arid area.