The ex plosion heat , specif ic volume and tox ic gas volume of expanded AN explosive at dif ferent oxygen balance value were studied in this paper. The follow ing result s w ere shown, w hen the oxygen balance value of expanded AN ex plosive dropped from - 0. 1 % to - 4. 5 %, the ex plosion heat w as reduced from 3 838. 71 kJ kg- 1 to 3 555. 99 kJ kg- 1, the specif ic volume w as increased f rom 960. 94 L kg- 1 to 985. 85 L kg- 1 and tox ic gas volume also increased from 1. 81 L kg- 1 to 63. 32 L kg- 1.