Abstract: Changes in land use can have important impacts on soil carbon and nitrogen storage. To explore the effects of different land use types on soil carbon and nitrogen storage, we examined the differences of soil carbon and nitrogen storage, ratio of carbon to nitrogen and root biomass in the 0-100 cm soil layer of the natural grassland and Pinus tabuliformis plantation since the implementation of the project (15 years) of “Returning Farmland to Forest (Grassland)” in the Ziwuling forest region of the Loess Plateau, China. The results showed that soil organic carbon of both natural grassland and P. tabuliformis plantation showed surface polymerization effect. Soil organic carbon storage in the 0-20 cm soil layer of natural grassland was significantly lower than that of P. tabuliformis plantation, while the other soil layers showed no significant difference. The total soil carbon storage of P. tabuliformis plantation in the 0-100 cm soil layer was 117.94 Mg·hm^-2, which was 28.4% higher than that of natural grassland. There was no significant difference in total nitrogen storage in different soil layers of the two vegetation types. The soil total nitrogen storage of natural grassland was 7.69 Mg·hm^-2 in the 0-100 cm soil layer, which was 17.7% higher than P. tabuliformis plantation. There was significant difference in ammonium storage among different soil layers in natural grassland and P. tabuliformis plantation. The ammonium storage in natural grassland was significantly higher than that in P. tabuliformis plantation, exhibited first increase and then decrease trend with the increases of soil depth. Only in the 0-20 cm soil layer, nitrate storage in natural grassland was significantly higher than the P. tabuliformis plantation. The ratio of carbon to nitrogen of natural grassland and P. tabuliformis plantation showed no significant difference in 0-20 cm soil layer. With the increases of soil layers, the ratio of carbon to nitrogen in P. tabuliformis plantation were higher than in the natural grassland, and the difference increased gradually. In addition, soil carbon and nitrogen storage showed significantly positive correlation with root biomass in natural grassland and P. tabuliformis plantation. Therefore, natural grassland was conductive to the accumulation of soil nitrogen storage, and P. tabuliformis plantation was beneficial to increase soil carbon storage. Root was an important factor affecting the distribution of soil carbon and nitrogen storage.