To investigate the differential regulation mechanisms of land use change on soil carbon and nitrogen fractions as well as carbon and nitrogen storage，this study took typical land use types(picea asperata:PA，hippophae rhamnoides:HR，Medicago sativa:MS，abandoned land:AL，and wheat field:WF)in the semi-arid region of the Loess Plateau in Longzhong as research objects in 2022.Through the combination of field positioning monitoring and indoor index analysis，the study explored the variation characteristics of soil physical properties，carbon and nitrogen fractions，and carbon and nitrogen storage in the 0-40 cm soil layer under different land use types.The results showed that，compared with the AL treatment，the soil porosity，water content，and water storage capacity of the PA treatment were increased by 1.45%，70.4%，and 73.4%，respectively；while the soil bulk density and pH value of the WF treatment were increased by 2.78% and 2.79%，respectively.The contents of soil organic carbon，dissolved organic carbon，easily oxidizable organic carbon，microbial biomass nitrogen，and soil dissolved organic nitrogenin each treatment were first increased and then decreased with the vegetation growth stage，and all decreased with the deepening of the soil layer.Furthermore，compared with the AL treatment，the PA，HR，and MS treatments significantly increased soil carbon and nitrogen storage；among which，the carbon storage was the highest under the PA treatment，reaching 15.6 t/hm²，while the nitrogen storage was the highest under the MS treatment，reaching 1.13 t/hm².Correlation analysis showed significant correlations among soil physical properties，carbon and nitrogen fractions，and carbon and nitrogen storage.Redundancy analysis showed that soil bulk density and soil organic carbon content had the highest explanatory power for carbon and nitrogen storage，accounting for 38.2% and 26.0%，respectively.In summary，land use patterns significantly affected soil carbon and nitrogen dynamics in the Longzhong Loess Plateau.PA，HR，and MS treatments all significantly increased soil carbon and nitrogen stocks，among which PA treatments had a relatively better carbon sequestration effect and MS treatments had a relatively better nitrogen fixation capacity.This technical system could provide an important theoretical basis for land management oriented to “carbon sequestration，nitrogen fixation，and sink increase” in the semi-arid regions of the Loess Plateau.