Aerobic composting is a method for sanitary disposal of human feces as has been used in bio-toilet systems. In this study, batch experiments were conducted using a closed aerobic composting reactor with sawdust as the bulky matrix to simulate the condition of a bio-toilet for sanitary disposal of human feces. Attention was paid to the Biodegration property of organic matter. Under a controlled condition of temperature(60°C), moisture content(60%), and continuous air supply, more than 70% fecal organic removal was obtained in a two-week composting period. Based on assumptions that the organic matter of feces was invided into two parts included degradation and undegradation, the organic matter’s biochemical degradation of similar level 1 dynamics model can build. Using the experimental data of composting reaction under thermophilic composting conditions, calculated out respectively reaction kinetics constants 0.4413. Thermophilic composting could be considered to reach more than 70% fecal organic removal, shortening maturity period of compost. The similar level 1 dynamics model improve design of composting reactor and use of bio-toilet.