【Objective】 Rhizosphere is a specific compartment that is significantly influenced by soil microorganisms in the plant root system in soil. Rhizosphere extends from the surface of the main root for a few millimetres, and is an important zone where plant-soil-microorganism interactions occur. In the rhizosphere, bacteria and fungi coexist and interact with each other, playing a critical role in recycling of nutrients in the ecosystem and sustaining of plant health and growth. Ecological network analysis can visualize interactions between microbial communities, and uncover co-occurrence patterns of the species in microhabitats and their main influencing factors, which provides a new approach to explaining complex structure of the microbial communities. Network analysis can also be used to explore mechanisms of microbial interactions driving biogeochemical coupling of important elements in soil, which is an important step towards predicting and improving service functions of a soil ecosystem. Unique in structure and composition, biochar can improve soil properties in a number of aspects, for instance, promoting formation of soil aggregates, enhancing cation exchange capacity, nutrient absorption capacity and water holding capacity, and dulling excessive acidification. So it can be applied beneficially to soil amelioration and raising of crop yield. In addition, the unique aromatic surface, excellent porous structure and high moisture and nutrient adsorption capacity of biochar can also provide soil microorganisms, such as bacteria and fungi, with benign habitats, and hence increase biomass of the microorganisms. The application of biochar can alter structure and enzyme activity of the microbial community, which benefits accumulation of soil organic matter and transformation of soil nutrients and then indirectly improves growth of the plants. Therefore, a comprehensive understanding of the effects of biochar on the interactions between bacterial and fungal communities in rhizosphere soil is of great significance to how to improve soil nutrient transformation. 【Method】 In order to explore effects of biochar on interactions between bacteria and fungi in rhizosphere soil, a pot experiment was designed to have CK and a treatment of adding 2% (w/w) biochar and performed for comparison in interaction network between rhizosphere bacteria and fungi and its affecting factors. The soil used in the experiment was collected from the topsoil layer (0~10 cm) of a paddy field in Changzhou, Jiangsu Province, air-dried, screened with a sieve 2 cm in mesh, and ground fine. Then the soil homogeneous in texture was left in rest for 24 hours, before being put in pots, 3 kg each. Full ryegrass seeds were sown into the pots, 30 each. Soil and plant root samples were collected from the pots on the 0th, 5th, 10th, 15th, 20th, 25th, 30th, 35th and 40th days after germination of the seeds, from three pots each time as replicate. So the experiment had a total of 54 pots of ryegrass plants. The samples were analyzed separately and soil geochemical properties, rhizosphere microorganisms, and morphological parameters of the ryegrass roots were determined. 【Result】 Network analysis shows that in the treatment, the association between bacteria and fungi in their co-occurrence network became more complicated with number of nodes and interaction enhanced. Positive interactions within the bacterial community and between bacteria and fungi communities were significantly enhanced (P < 0.05). Modular analysis of the interaction networks in CK and Treatment found two modular structures with highly interconnected nodes. In the treatment, Flavobacterium was found to be the key group of the co-occurrence network, while in CK, Sunxiuqiniaand Pichia were. Mantel test indicates that soil pH (r= 0.385, P = 0.003) and soil ammonium nitrogen (r = 0.501, P = 0.003) had more significant effects on the interaction between rhizosphere bacteria and fungi in the treatment. 【Conclusion】 Application of biochar significantly enhances interactions between bacterial-fungal communities in the rhizosphere soil, while improving positive associations within the bacteria community and between bacteria and fungi.