Abstract: This study evaluated the effects of material ratio, turning and ventilation on bio-drying of dewatered sludge and the changes of calorific value. Results showed that the peak temperature was the highest and reached 54.6℃ when the sludge and garden waste ratio was 5:2. The moisture content decreased by 11.22% with the highest VS degradation rate. Compared with no turning, the final water content of turning process was 45.95%, 2.54% lower than that in no turning. The ventilation rate of oxygen was 0.5m3/h in the experiment was conducive to the increase of the pile temperature and strengthening the drying effect. The moisture content of the pile pre-dried with optimal condition decreased from 60.45% to 42.57%. The low calorific value of dried material reached 9763.3kJ/kg. The utilization of calorific value has a good prospect.