Sewage sludge and papermaking sludge samples with different surface ratios (1.62, 2.16, 3.24 and 6.48 cm²·g^-1) and different temperatures (30, 70, 102 and 130℃) were analyzed through experiment on their drying characteristics. The results indicated that the higher the temperature and the surface ratio were, the less time was used for sludge drying. When the water loss was less than 10%, the sludge was in the fast drying phase; when the water loss was between 10%-60%, the sludge was in the constant drying phase; when the water loss was more than 60%, the sludge was in the reduced drying phase. In each drying phase, the water loss rate of sewage sludge was 0.01%·s^-1 less than that of papermaking sludge.