The invention discloses a disk type 
water cooling self-excited 
eddy current retarder, which comprises a 
stator component, a rotor component, a 
drive shaft and a cooling water circulating device, wherein the 
stator component is composed of two 
stator disks and a plurality of permanent 
magnetic field generating devices; a cooling 
water channel is disposed in each of the stator disks; two permanent magnets and a partition board are disposed in a cavity of a magnetic conductive sleeve in each of the permanent 
magnetic field generating devices, and the two permanent magnets are so arranged that 
magnetic poles are in opposite directions; the partition board is fixedly adhered to a cylinder which is formed between the two permanent magnets, corresponds to the cavity of the magnetic conductive sleeve, and is capable of rotating along a central shaft of the magnetic conductive sleeve; and a through groove port which faces an armature is formed on the side wall of the magnetic conductive sleeve; when a 
retarder is in a work state, magnetic lines of force of permanent magnetic fields form a 
magnetic field loop through the two permanent magnets, the magnetic conductive sleeve, an air gap and the armature; and when the 
retarder is in a non-work state, magnetic lines of force of magnetic fields form a magnetic conductive loop through the two permanent magnets and the magnetic conductive sleeve; current is provided for magnetic exciting coils by a self-generating device, therefore, no vehicle-mounted power supply is needed to provide power; and cooling liquid can take away partial heat generated when the retarder brakes.