The work aims to investigate the fundamental principle and characteristics of acoustic emission signal generated by the jet flow field resulting from gas leakage in steel drums that excite the drum body. The flow field state from steel drum gas leakage was analyzed with Fluent software for computational fluid dynamics (CFD). The jet model and mechanism of gas leakage in steel drum were introduced. The mathematical model was built with finite element method for CFD. The geometrical model and boundary conditions of steel drum leakage were established. The relevant parameters of the simulation analysis were set. The simulation results of steel drum leakage were obtained under different internal pressures, different leak diameters and multiple leaks. The distribution situations of airflow velocity fields, pressure fields and other parameters of steel drum leakage were discussed. The results showed that the airflow velocity during the steel drum leakage played a leading role in the acoustic emission signal, and the effect of internal pressure on airflow velocity was large, and the influence of hole diameter and leak quantity was small. The simulation analysis of the flow field from gas leakage of the steel drum provides reference for the investigation on the leakage mechanism of the steel drum and the detection of the acoustic emission excitation signal.