Conservation tillage, a new kind of cultivation technique or agricultural practice includes no-till, reduced tillage and straw mulching. The aim of conservation tillage is to protect the environment, improve soil quality and save farming cost. Straw degradation plays a very important role in implementation of conservation tillage. Therefore, it is of great significance to study diversity of cellulose degrading bacteria in the soils different in conservation tillage practice. Currently, scholars at home and abroad have been doing a lot to study cellulose degrading bacteria, focusing mainly on screening and isolating of cellulose degrading bacteria and cloning of cellulose degrading gene. But little has been reported on diversity of cellulose degrading genecbhⅠ. It is, therefore, necessary to do something in depth on diversity of cellulose degrading gene cbhⅠ in soils under different conservation tillage practices. Hence, effects of four conservation tillage practices, i.e. C_ntW_tS (tillage with mulching), C_ntW_ntS (no-tillage with mulching), C_ntW_t (tillage without mulching) and C_ntW_nt (no-tillage without mulching) were explored on diversity of cellulose-degrading bacteria in typical fluvo-aquic soil in the Huang-Huai-Hai Plain. Cellulose degradation bacteria in soils of different treatments were counted using the traditional plate colony counting method, and diversity of cellulose-degrading gene cbhⅠ was analyzed using the PCR-RFLP techinique (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). Results show that Treatment C_ntW_ntS was 148% higher than Treatment C_ntW_nt in population of cellulose-degrading bacteria, and Treatment C_ntW_tS was 130% higher than Treatment C_ntW_t, too. And the four treatments were all quite rich in cbhⅠ genotyping, amounting to 44 OTUs in total. Treatnent C_ntW_ntS was found to have 35 OTUs, Treatment C_ntW_tS 34 OTUs, Treatment C_ntW_nt 30 OTUs and Treatment C_ntW_t 30 OTUs, indicating that straw mulching could increase the number of cellulose-degrading bacteria that can decompose the straw, releasing nutrients into the soil. Analysis of diversity index shows that Shannon-Wiener index varied in the range between 3.09 and 3.36, and that straw mulching and no-tillage improved the diversity of cellulose degradation bacteria. Phylogenetic analysis shows that the cellulose-degrading bacteria in the libraries mainly belong mainly to Basidiomycota and Ascomycota. And Basidiomycota is the dominant phylum. Tillage and no-tillage have some influence on Basidiomycota, but almost none on Ascomycota. Meanwhile, a large number of uncultured cellulose-degrading bacteria were found living in the soils. Therefore, it can be concluded that conservation tillage, like no-tillage and straw mulching, can significantly increase the number of cellulose-degrading bacteria and enrich its cbhⅠ gene diversity.