The overall objective of this study was to provide some references for large-scale drying treatment of particular industrial sludge such as oily sludge. Considering the features of oily sludge as well as the characteristics of solar drying, solar dryer was designed and established in order to conduct the sludge drying treatment under sealed and low-temperature condition. The major parts of solar dryer were air collector and drying chamber. Drying treatment of oily sludge after conditioning and dewatering was performed with the designed solar dryer. The main measurements were temperatures of major components of solar dryer and water content of sludge. The experimental result indicates that the water content of oily sludge can be decreased by a maximum of 18% in use of the designed solar dryer. It is also proposed that the emitted volatile hydrocarbon and alcohols be recycled and the dried sludge be incinerated.