Abstract: In laser-cluster interaction experiment, the gas target is usually generated by stuffing gas into vacuum chamber in high flow velocity via supersonic gas jet under the condition of very high backing pressure. To acquire the density distribution characteristics of the gas target in different experimental conditions, the density distribution of the gas target was measured with M-Z interferometry, and the fringes were obtained at different backing pressures, temperatures and time lapses. The total spatial distribution of gas molecular density under different experimental conditions was obtained via the interferometer pattern measured by Fourier transformation based fringe processing. The experiment shows that M-Z interferometer can effectively measure the gas target density distribution produced by the supersonic gas jet. The fringe processing method based on Fourier transformation is accurate and has real-time feature. Therefore, it provides the possibility for the real-time measurement of gas target density during targeting practice.