Abstract: In this paper, the concept of Numerical Fuel Rod is proposed, and the technology of multi-physical modeling is studied. The thermal conduction module, the mechanical module（both based on finite element method） and the neutron transport module（based on method of characteristics） have been programmed and tested. The calculation results show that the modules are effective, which lays a solid foundation to achieve the multi-physical-coupling calculation and simulate the fuel rod behavior in the reactor.