The invention relates to a disc type sludge drying system based on cascade utilization of energy. The system comprises a disc type drying system and a filter-press drying system, wherein the disc type drying system comprises a casing, a stirring shaft is mounted in the casing, discs are mounted on the stirring shaft in a spaced manner, a sludge inlet and a steam outlet are formed in the top of the casing, a dry sludge outlet is formed in the bottom of the casing, the stirring shaft is driven by a stirring motor at one end, the stirring shaft adopts a hollow structure, one end of the stirring shaft is a hot steam inlet, and a condensed water outlet pipe is inserted into the end; the filter-press drying system comprises a filter-press system, a sludge feeding system connected with the filter-press system, a vacuumization system, a hot water circulating system and a sludge output system, the sludge feeding system is connected with a sludge feeding end of the filter-press system, the sludge output system is connected with is connected with a sludge discharging end of the filter-press system, the vacuumization system is used for keeping the filter-press system in a negative pressure state during filter pressing of sludge, and the hot water circulating system is connected with the steam outlet of the disc type drying system.