The invention discloses a method for muzzle efficiency testing. The method has the beneficial effects that a collision plate and a steel ball are arranged at the rear part of a gun, a collision methodis adopted, a standard gun is tested to shoot a special reduced charge bomb under the condition of carrying a gun muzzle brake or not carrying the muzzle brake; then the correlation calculation is carried out; according to the momentum conservation and the gun design philosophy, firstly, the free recoil speed and the recoil kinetic energy of the gun are calculated when the reduced charge bomb isshot; then the efficiency eta' of a reduced charge gun muzzle, the full charge and the reduced charge gunpowder gas action coefficients beta and beta', and the structural characteristic quantity Kof a gun muzzle device are obtained; finally the efficiency eta of a full charge gun muzzle is calculated, and the link of the measurement is reduced; and the method has the characteristics of convenience in operation, small in testing workload and high in precision, and can be used for design and improvement of the gun muzzle brake.