Underwater explosion properties of an aluminized explosive were numerically modeled by two burn techniques; a programed-burn and a reaction rate calibrated from two-dimensional steady-state detonation experiments. The programed-burn technique did not reproduce experimental data well; 33% error in peak pressure of shock wave and 9% error in bubble period. The rate reproduced the experimental observations very well; 7% error in peak pressure and 2% error in bubble period. The shock profile also agreed very well with experimental observation. These results demonstrates that the underwater explosion properties for aluminized explosives can be calculated only when the slow energy release is modeled properly.