In order to research the effect of molding powder flow on technique adaptability and charge safety of step-press-loading, the flow and packing density of different powder have been measured. Through the experiment of step-press-loading charge technique, the results show that the flow of explosive during proper area can adapt to technique of step-press-loading charge techniques. By reducing flow of explosive, explosive loading density can be increased locally, but radial density uniformity and loading safety become worse. Having moderate flow, loading density of step-press-loading charge can enhanced with the increase in packing density of explosive.