To promote the resource utilization of retired HTPB propellants， composite gel explosives were prepared by compounding them with energetic gels： the three-component propellant-containing composite explosive 1-PxDyϕz， the quaternary propellant-containing composite explosive 2-PxDyϕz that contains 9% RDX， the propellant-containing composite explosive 3-PxDyϕz that contains 15% RDX， and the propellant-containing composite explosive 4-PxDyϕz that contains 20% HMX. （x represents the content of propellant P， x=30%， 40%， 50%， y is particle size， y=5， 10， 15 mm； z denotes the charge size， z=40， 50， 65 mm）. Tests on detonation velocity， witness plate damage， and underwater explosion energy were conducted to investigate the energy characteristics of these composite gel explosives with varying propellant content， particle size， and charge diameter. The results indicate that an increase in the propellant content in 1-PxDyϕz and 2-PxDyϕz composite explosives reduces the detonation velocity and brisance of the composite explosives， whereas increasing the propellant content in 3-PxDyϕz and 4-PxDyϕz increases both detonation velocity and brisance. The decrease in propellant particle size from 1-PxDyϕz to 4-PxDyϕz contributes to the increase of detonation velocity and brisance， and the increase in charge diameter significantly increases the damage capability. Results of underwater explosion tests show that an increase of propellant content in 1-PxDyϕz and 2-PxDyϕz reduces the total underwater energy output， while 3-PxDyϕz has a relatively constant total energy with an increase in propellant content， and 4-PxDyϕz has an increasing total underwater energy with an increased of propellant content. Additionally， the total underwater energy from 1-PxDyϕz to 4-PxDyϕz increases with the decrease of propellant particle size.