The invention discloses an energy-saving type 
sewage sludge harmless treatment method. The method includes the following steps of firstly, conducting continuous freezing on 
sludge through a 
freeze drying energy circulation 
system, and unfreezing the 
sludge after continuous freezing; secondly, conducting 
dewatering on the sludge, completely processed through freezing and unfreezing, in a filter pressing device, so that sludge with the low 
moisture content is obtained through filter pressing; thirdly, smashing the sludge in a smashing device; fourthly, conveying smashed sludge particles into a sludge 
drying device to be dried, dissipating heat through the 
freeze drying energy circulation 
system by means of a condenser, and transferring heat to air; fifthly, sending the sludge particles into an incinerator to be incinerated, making generated high-temperature 
smoke enter a 
waste heat boiler, making air heated by the condenser enter a second 
heat exchanger to continue to absorb heat, and unfreezing the sludge and 
drying the sludge particles through the formed high-temperature air. By means of the method, the sludge 
processing amount cannot be increased in the treatment process, and due to recycling of working 
medium energy, the freezing efficiency and the heat 
utilization rate of the sludge are increased.