Abstract: A kind of automatic control software for composting is designed by using Microsoft Visual Basic computer language and tools including Microsoft Access & Excel. The software -TOT- can control aeration system of composting by temperature, oxygen content of the exhausted gas, and time. Maximum altering temperature, minimum oxygen content of the exhausted gas, and distinguished temperature of different phases can be set by users. The composting temperature, oxygen content of the exhausted gas, and pH value can be monitored by the system. The results are refreshed per 10 s, and saved automatically per 1 h. The data can also be gathered from database and analyzed by using Microsoft Excel. The simulating operational results show that the system software can control fans according to the scheduled requirement, can calculate and record the phase and operational time of fans correctly, can display and save the data. In addition, the software can also read the data of composting temperature and oxygen content of the exhausted gas, and draw the profiles of them.