Abstract: Muzzle brakes can control the outflow of powder gas,reduce the backlash, and improve the maneuverability of artilleries. In thispaper, muzzle flow field of a musket without a muzzle set is simulated byEuler Equation and LU Decompositions Method. The computation results agreewith the experiment results very well. The muzzle flow field of an artillerywith a muzzle brake is also simulated. The main characteristics and themutual relations of shock waves in the muzzle flow field are obtained by thesimulation. On the basis of the simulation results, the influencesof the brake holes on the muzzle brake capabilities are analyzed. Thedetails of the muzzle flow field in this paper will be useful in the studyof the holistic capability of the muzzle brakes.