Abstract: Based on MELCOR which is the severe accident analysis integration program, the accident of SG-tube rupture coupled with whole ship blackout was researched.Considering the release of radioactive material to other cabins in the case of SG-tube rupture, the release, migration, retention and distribution characteristics of the noble gas and CsI were analyzed. The result shows that steam pipe of the secondary loop would be overpressure failure and hydrogen combustion would result in overpressure failure of the adjacent ones of reactor cabin. At the end of the computation, about 99.61% of Xe and 49.96% of CsI in total cumulative amount were released from the reactor core. In cabin Ⅰ and Ⅱ, the distribution fraction of Xe was 38% and 18%, and it was 22.2% and 2.7% for CsI respectively. CsI was mainly resided in the bottom pool of the reactor cabin, and a small amount of the CsI was leaked to the cabinⅡ. The analysis results will provide help for further analysis on the source dose and for emergency inside and outside the ship.