Numerical research on the flow field characteristics of the cylindrical membrane inflation was performed by the Euler-Lagrangian method. The results show that bumps are formed at two ends of the cylindrical membrane

swinging vertically during the inflation within inlet velocity range (50-90m/s) and inlet pressure range (1.0-1.4MPa). With the analysis on the flow structure

vorticity transportation and the mechanism of vortex/shock interaction in the flow field inside the cylindrical membrane

it is found that there is a cured shock adjacent to the inlet tube

making flow deflection. Vortexes formed by the deflected flow interact with shock

resulting in local supersonic zones. Based on the discussion about cylindrical membrane stress distribution

the local stress concentrations at the top and two ends of the cylindrical membrane are considered as important factors influencing the safety and stability. Comparing the results of different inlet pressures and velocities

it is found that the influence on safety caused by the inlet velocity is less than the inlet pressure

and the influence on stability caused by the inlet velocity is greater than the inlet pressure.