Abstract: Based on the subchannel model and the wire wrap distributed resistance model, the subchannel code ATHAS-LMR was developed to analyze the thermal-hydraulic performance of the LMFBR (liquid metal cooled fast breeder reactor) fuel assemblies. Comparing the results of ATHAS-LMR with those of some foreign experiments and similar subchannel codes, the results show that ATHAS-LMR can predict the experiments very well and is able to analyze the thermal hydraulic performance of the LMFBR fuel assemblies under different conditions, such as normal operation, flow blockage accident.