Four modified single-base propellant(SB projpellant) samples with different contents of nitroglycerine(NG) were prepared using D-5/7 SB propellant as base raw material, fixating polyester content and controlling added amount of NG.The effect of NG content on the combustion progressivity of modified single base propellant was studied by FTIR, closed-bomb test and 14.5 mm gun test. Results show that the greater the NG content in modified single base propellant, the greater the permeation depth of NG, the better the combustion progressivity of modified single base propellant and faster the muzzle velocity of modified SB propellant.In comparison with D-5/7 SB propellant, the muzzle velocity of sample E4(12% NG) increases by 82.5 m·s^-1(8.35%).