The invention belongs to the field of cladding designs of a fusion and 
fission hybrid reactor, and particularly relates to a Th-U self-sustaining circulating full fused salt fuel 
hybrid reactor system and an operation method thereof. The Th-U self-sustaining circulating full fused salt fuel 
hybrid reactor system is characterized in that a fast 
fission breeder reactor provides an initial easily 
fission fuel required by starting of a thermal 
fission reactor, a cladding design of the thermal 
fission reactor utilizes an arrangement strategy of a seed-cladding to improve the entirety 
neutron economy of the 
system, and the purposes of a 
high energy enlargement factor of the 
system, 
tritium breeding and 
thorium-
uranium self-sustaining circulating of the 
system are realized; <233>U is loaded in an energy generating region, so that the energy generating region has a good neutronics property and is mainly used for realizing the purposes of energy amplification of the system, 
neutron multiplication and most <233>U breeding of the system; superfluous neutrons enter a 
tritium producing region and are used for 
tritium breeding and part of <233>U breeding of the system. According to the 
hybrid reactor, due to self-sustaining circulating of 
thorium and 
uranium, a 
thorium fuel is converted into <233>U and is gradually burn up in an operation process, and the Th-U self-sustaining circulating full fused salt fuel 
hybrid reactor system can effectively and stably operate for a long time just by gradually adding the thorium fuel and removing the generated fission product.