To elucidate the atomization process of a liquid jet across a high-speed airstream, the spray shape, the mass flow rate per unit area and the Sauter mean diameter were measured. Under an airstream velocity of 140m/s or 70m/s and injection velocity of 10m/s, 20m/s or 40m/s, the Sauter mean diameter and the maximum liquid mass flow rate per unit area in the spray hardly changed with the liquid injection velocity. However, with increasing air velocity, the Sauter mean diameter decreased and the maximum liquid mass flow rate per unit area increased. Rearranged spatial distribution of the liquid mass flow rate per unit area in a horizontal direction agreed with the profile by the Gauss's function. An equation for width of spray was obtained from the photographic results.