To explore the influence of liquid counter-mass on the backblast flow field in recoilless rifle, experimental and numerical studies were conducted on the liquid counter-mass launch process of the recoilless rifle. A comparative analysis was performed on the characteristics of the backblast flow field with and without the liquid counter-mass. Experimental results indicated that the liquid counter-mass can reduce the development speed of the backblast flow field and eliminate the flame during the launching of the non-recoil rifle. When calcium chloride solution was used as the equilibrium body, the flame suppression effect was weaker than that of pure water, but the smoke suppression effect was stronger. Numerical results showed that the development velocity and the axial and radial displacement of the backblast flow field with the liquid counter-mass were obviously slower than those of the pure gas jet flow field, along with a certain cooling effect. This was attributed to the interaction between the pure gas jet and the liquid working medium, which inhibited the formation and development of expansion-compression wave system, reducing the number of shock waves.