The greenhouse effect has become increasingly serious globally. Nitrous oxide (N_2O) is both the major ozone depleting substance and a potent greenhouse gas having a global warming potential 298 times that of CO_2, and the N_2O concentration is still increasing at an annual rate of about 0.8 *10~(-9). Nitrous oxide reductase (N_2OR) can reduce N_2O to N_2, and until recently, the nosZ gene was the only gene known to be able to encode N_2OR. Besides the well-known nosZI, a new lineage of the N_2O-reductase (nosZ clade II), which is abundant and widespread in soils, has been identified. In this paper, the main characters of nosZII-containing microbial communities and the related working mechanisms are summarized. In addition to the main differences between nosZI and nosZII, the important environmental factors that regulate the composition, abundance, and expression of nosZII-containing communities are also discussed in this paper. Studies have shown that nosZII communities are distributed among a diverse range of bacterial and archaeal phyla, such as Epsilon-proteobacteria, Bacteroidetes, and Aquificae. Interestingly, most of the nosZII microbes lack a nitrite reductase encoding gene (nirS or nirK) and are therefore unable to denitrify, indicating the importance of these communities as N_2O sinks. Soil properties such as texture, pH, C/ N ratio, temperature, and lake physical gradient could regulate nosZII microbe abundance and diversity, and the pH and C/ N ratio may be the most important influencing factors. Studies on the ecological function of nosZII microbes have advanced considerably with the development of molecular biology technology. However, further studies on the community structure of nosZII microbes, the influencing factors of nosZII microbe abundance and diversity, and characteristics of nosZII strains with strong N_2O reducing ability are needed. We hope to provide a theoretical basis that can be used to facilitate N_2O reduction and relieve the greenhouse gas problem.