To study the effect of sensitizing methods on the detonation performances of MgH₂-based hydrogen storage emulsion explosives, the underwater explosion and brisance testing experiments of two kinds of hydrogen storage emulsion explosives were carried out. With the help of experimental data and theoretical analysis, the relationships between the work capability and brisance of MgH₂-based hydrogen storage emulsion explosives were studied and the theory of using the specific impulse to express the brisance of explosive was adjusted. The results show that in the physical and chemical sensitization of MgH₂-based hydrogen storage emulsion explosives, MgH₂ powders play the roles of energetic additive and chemical foaming agents, respectively. Compared with the chemical sensitization, the specific shock wave energy, specific bubble energy and total energy of the physical sensitization of MgH₂-based hydrogen storage emulsion explosives are decreased by 11.98%, 5.38% and 8.66%, respectively, but its brisance (lead block compression value) is increased by 5.15 mm, which means that sensitizing methods have significant impact on the work capability and brisance of MgH₂-based hydrogen storage emulsion explosives.