Abstract: Abstract: Composting is a sustainable and environmentally friendly method for dealing with animal manure which could bring great pollution to the environment without reasonable disposing. But the conventional composting usually needs very long time to reach stable and matured, accompanied with amounts of nitrogen nutrients loss either. Porous materials are often added into the composting pile as bulking agents to solve these problems due to some good properties in these materials, such as high porosity, great specific surface area and adsorption capacity. In this study, 3 kinds of porous material (ceramsite, semicoke and biochar) were chosen as the bulking agent and a control group added with no porous material was set. Especially ceramsite and semicoke were utilized in composting for the first time. Biochar is the porous bulking agent with the highest usage frequency and with excellent efficiency on enhancing composting process, but biochar is expensive. A 14 d lab-scale continuous thermophilic composting method was used for the composting of dairy manure and corn straw by controlling the entire composting process at a thermophilic environment of 55 ℃. Comparisons about effects of these materials on the biodegradation and NH3 emission of dairy manure and other properties were investigated. The results showed that all the 3 materials could accelerate the biodegradation of the waste and reduce the NH3 emission. After 14 d composting, the organic matter loss ratio of the control group was only 21.28%, but the total NH3 emission of the control group was the most (182.75 mg) compared with other treatments. Compared with the control group, the group added with biochar had an increase of 17.19% in the organic matter loss ratio (38.47%) and decrease of 12.8% in the total NH3 emission (159.38 mg). Group added with ceramsite and biochar had less organic matter loss ratio (32.8% and 33.0% respectively) and more NH3 emission (172.81 mg and 166.01 mg respectively) than biochar group, but had much better effects compared with the control group. Water soluble carbon of all groups attained the maturation standard (≤5 mg/g dry weight), except the control group. The degradation ratio of water soluble carbon of ceramsite, semicoke and biochar groups (54.78%, 48.71% and 59.54% respectively) were higher than the control group (45.34%), indicating that the addition of ceramsite, semicoke and biochar could promote the maturation of compost. Many other parameters like temperature, pH value and electronic conductivity value were also analyzed, but there were not significant differences among the groups. In a conclusion, the porous material as bulking agent could improve the microbial activity, accelerate the biodegradation of the organic and reduce the NH3 emission during the composting of agriculture waste. Better effects were revealed in biochar group, but ceramsite and semicoke were much cheaper. Furthermore, not like the fragile and easily destroyed biochar, ceramsite and semicoke have stable physical structure which makes them recyclable. So there are great prospects for the utilization of ceramsite and semicoke in composting, espectively semicoke which is a solid waste from the oil refining industry, but further investigation needs to be conducted.