The Ulmus glaucescens woodland is the largest vegetation type in the Helan Mountain natural reserve areas.Research on the organic carbon storage of the woodland is useful for evaluating ecological service functions of the area.The biomass,vegetation carbon content and soil organic carbon of the woodland were sampled and measured on the east side of Helan Mountains and the carbon storage was evaluated.The carbon contents varied in the different parts of Ulmus glaucescens.The trunk carbon content rate was higher than other parts and average carbon content of Ulmus glaucescens was 437.78g/kg,lower than other forest species.The carbon density of understory and roots was 276.61g/m².The soil carbon content was 15.82g/kg,higher than other soil type,and the carbon density was 3.76kg/m².Average organic carbon density of the woodland was 4.72kg/m².Carbon storage per hectare was 47.2t.Soil carbon storage was significantly higher than vegetation carbon storage.In the sparsely vegetated arid area,soil conditions are of benefit to the organic carbon accumulation.Soil organic carbon in arid zone is an important organic carbon pool.