The utility model discloses a frostless type dehumidification system of low temperature, include the evaporimeter, reheat condenser, the centrifugal fan that set gradually according to the air current flow direction, the induction port of tube coupling compressor is passed through in the export of evaporimeter, and water -cooled condenser's import is connected to the gas vent of compressor, and water -cooled condenser's export is divided into two branch roads, and the export and the cistern import of reheat condenser are connected respectively to first branch road, the import of cistern exit linkage evaporimeter, and first is equipped with first solenoid valve on the road, and the entry of reheat condenser is connected to the second branch road, still including the supplementary system of preheating, the supplementary system of preheating is used for preheating the back to the air that gets into in the dehumidification system, makes the air that is preheated loop through evaporimeter, reheat condenser, centrifugal fan and dehumidifies. Dehumidification system operation under low temperature working condition need not rely on the defrosting, can realize that unit continuous operation does not frost, to evaporimeter import preheating of air, avoid the evaporimeter to frost, realize unit low temperature working condition steady operation.