Abstract: Orthogonal test taking the viscosity and hardness for measuring performance index was proposed to optimize the bonding system and improve energy output of PBX. Test results of the underwater explosion with PBX optimized show that the ratio of binders is HTPB/DBP/IPDI/TPB=50:50:4.6:0.06, and the energy of explosive is 1.13 times the original TNT equivalent. The optimization of bonding system is a new method to improve the energy of PBX.