The effects of growing grass on soil nutrients，organic carbon components and enzyme activities in walnut orchards were explored to provide theoretical basis and basic data for walnut orchard soil management in this study.Taking the soil of Fenyang walnut orchard as the research object，six treatments of soybean，vetch，farrow pea，ryegrass，natural grass and clear ploughing were set up，each treatment repeats 3 times and the variation characteristics of soil nutrients，organic carbon components，and soil enzyme activities in the walnut orchard’s different soil depths(0 ～ 60 cm)were studied.The results showed that as the depth of the soil layer increased，the soil nutrient content，enzyme activity，and soil organic carbon component content showed a decreasing trend，and grass had the greatest impact on the 0 ～ 20 cm soil.In the 0 ～ 20 cm soil layer，compared with clear tillage，ryegrass treatment significantly increased the content of soil available phosphorus and available potassium，which were 1.18 and 1.15 times of that of clear tillage.The content of total nitrogen and alkalihydrolyzable nitrogen in the soil of treatments with legumes(farrow pea，vetch，soybean)increased by 17.0% ～ 19.3% and 9.7% ～ 11.7%，respectively.The contents of total organic carbon(TOC)，light fraction organic carbon(LFOC)，dilutable organic carbon(DOC)，particulate organic carbon(POC) and readily oxidizable organic carbon(ROC)of planting ryegrass increased by 21.3%，46.0%，40.1%，12.8% and 37.0%，respectively.In 20 ～ 40 cm soil layer，the contents of TOC，LFOC，DOC，POC，ROC of planting ryegrass treatment increased by 16.1%，46.0%，22.7%，8.2% and 25.3%，respectively.Leguminous plant(soybean)treatment significantly increased soil urease activity(P<0.05)by 16.0%； ryegrass treatment significantly increased soil invertase，phosphatase，and catalase activities (P<0.05)by 10.2%，32.5% and 121.4%，respectively.Therefore，it is necessary to choose different grasses for planting according to the soil fertility status.