Abstract: 【Objective】 To investigate the effects of conservation tillage on vegetative organs and yield of spring wheat in the semi-arid area of Loess Plateau.【Method】 Using the method of combined field and laboratory experiment,an experiment was conducted in Anjiapo Village,Anding District,Dingxi City,Gansu Province. The stoichiometric characteristics of roots,stems,leaves,medium OC,TN,TP,dry matter accumulation and distribution,and yield of spring wheat under different tillage treatments（traditional tillage（T）,no-tillage（NT）,traditional tillage + straw mulch（TS）,and no-tillage + straw mulch（NTS）） at different growth stages were analyzed.【Result】 The contents of root,stem,leaf,medium OC and TN of spring wheat under no-tillage + straw mulch increased to different degrees,while the contents of TP tended to be stable,N∶P and C∶P were higher than those under other treatments,and C∶N was lower;the contribution rate of dry matter accumulation to grain under no-tillage treatment increased by 32. The contribution rate of dry matter accumulation to grain under the no-tillage treatment increased by 32. 44% compared with that under the ploughing treatment,and the contribution rate of dry matter accumulation to grain under the straw mulch treatment increased by 38. 34% compared with that under the no-mulch treatment;NTS treatment promoted post-anthesis dry matter accumulation and transport,significantly increased the number of panicles and 1 000 grain weight,and increased yield by 24. 79%,14. 95% and 10. 26% compared with T,NT and TS,respectively.【Conclusion】 No-tillage and straw mulch tillage are more suitable for improving the yield of spring wheat in semi-arid areas of the Loess Plateau.