Considering the main problems of the small working volume, less functional on real time monitoring and feedback control of current experimental composting reactor system, an experimental type of aerobic composting reactor system was designed and manufactured on the basis of existing research. According to the principle of statics and thermodynamics, the key functional units of the composting reactor system were optimized. Automatic control system for the aerobic composting reactor was introduced for a better control of composting process. Testing experiments were carried out to check the usability of the designed composting reactor system. The period of composting temperature higher than 50℃ lasted 8.1, 7.2 and 4.8 days for each layer in the reactor system, respectively. The final pH value is less than 8 for composting materials of all layers. The final germination index (GI) for composting product of each layer are higher than 85%, respectively. All the three results show that the composting reactor performs well.