【Objective】The objective of the study was to investigate effects of tillage on soil bacterial diversity and soil properties in upland under a wheat-bean rotation system.【Method】A long-term stationary field experiment was started on tillage in an upland in Central Gansu in 2001. The experiment was designed to have four treatments, i.e. Treatment T (conventional tillage), Treatment NT (no tillage), Treatment TS (conventional tillage with straw returned), and Treatment NTS (no tillage with straw mulched).【Result】Results show: 1) Compared with Treatment T, Treatments NTS and TS significantly increased the contents of soil organic carbon, soil total nitrogen, soil microbial biomass carbon and soil microbial biomass nitrogen in the 0~10 cm and 10~30 cm soil layers, especially Treatment NTS, which increased the contents of soil organic carbon, soil total nitrogen, soil microbial biomass carbon and soil microbial biomass nitrogen by 28.27%, 114.16%, 13.51% and 49.14%, respectively, in the 0~10 cm soil layer and by 39.86%, 98.05%, 10.78% and 40.72%, respectively, in the 10~30 cm soil layer; 2) Acidobacteria (26.42%), Proteobacteria (19.86%) and Actinomycetes (19.44%) were the main dominant groups of bacteria, accounting for 26.42%, 19.86% and 19.44%, respectively, of the total population of the soil bacterial community in the upland. Treatment NTS increased the abundance of the three groups by 35.11%, 33.77% and 30.17%, respectively; and 3) Compared with the traditional tillage, the three conservation tillage practices increased the soil microbial in the 0~30 cm soil layer in Observed-species index, Chao index, Shannon index and Simpson index, and the effect of treatment NTS was the most significant.【Conclusion】Therefore, conservation tillage practices such as no-tillage with straw mulching would not only increase soil carbon and nitrogen sequestration, improve abundance and diversity of the soil bacterial community and soil biological activity, but can also promote sustainable development of the agriculture in the dryland farming area of Central Gansu.