In order to further improve the combustion performance of the modified single base gun propellant, the modified single base gun propellants 1^# and 2^# were prepared via the energy-increased and desensitized process to the 5/7 single base gun propellant with web of 0.55 mm. The solvent extraction process was adopted in the energy-increased and desensitized process of preparing the sample 2^#. The surface appearance was investigated by SEM. The bulk densities were determined by a standard container method. The combustion performances under constant volume were analyzed by a closed bomb test. The results show that the structure of propellant 2^# is solidish. The bulk density of propellant 2^# is increased from 0.888 g·cm^-3 to 0.920 g·cm^-3. The initial combustion of propellant 2^# is steady and the grain split point is delayed from 6.0 ms of propellant 1^# to 7.0 ms of propellant 2^#. The combustion end is delayed from 6.0 ms of propellant 1^# to 8.0 ms of propellant 2^#. The combustion progressivity of propellant 2^# is enhanced, revealing that propellant 2^# has an excellent combustion performance.