Abstract: In order to accurately analyze the cooling performance and temperature distribution of the sodium-cooled fast reactor debris bed in the boiling, drying and channel drying phases, and to improve the calculation efficiency, COMMEN-LT was developed based on the COMMEN program and the DEBRIS-HT program, combining their respective computational advantages. In order to verify the calculation results of the COMMEN-LT program, the ACRR-D10 experiment of Sandia Laboratory in the United States was selected for comparison. The results show that the COMMEN-LT program can well simulate the heat exchange mechanism and temperature distribution of the debris bed in the initial stage of heat transfer, boiling stage and channel drying.. The calculation time is reduced to the level of “second”, which saves huge calculation costs and greatly improves the calculation efficiency.