Abstract: Under some certain conditions in Hartmann-Sprenger (H-S) tube there can be resulted in intense jet oscillation at a specified frequency.The oscillation flow in the H-S tube was investigated numerically and experimentally.The numerical simulation results indicate the periodical changes of the flow field while the transient schlieren images of the corresponding case show the taking-in jet and the taking-out shock wave.Those results reveal the mechanism of the excited oscillation in the H-S tube.Based on the experimental data,the expression for estimating the oscillation frequency in the small-diameter case was modified which can help to design the jet nozzle at a given excitation frequency.