The transient image of the liquid jet in supersonic crossflow was obtained by microphotography method and the spatial resolution was 1.57 μm/pixel. The evolution of the surface wave was phenomenologically analyzed. The 3D flow field and liquid column structure were numerically investigated through volume of fluid method and the gasliquid interaction was discussed accordingly. The primary breakup of liquid jet experiences two physical processes: the column breakup and the surface breakup. The column breakup is dominated by RT instability from gasliquid acceleration while the surface breakup is dominated by KH instability from gasliquid shearing. The oscillation of the local pressure around the jet surface should be the main mechanism of the generation and evolution of the surface wave. The recirculation flow generates leeward the jet column since the interaction of the supersonic flow and the continuous liquid column. Therefore, the spray near the bottom wall contains two portions: the shearing spray from the surface breakup and the transporting spray through the recirculation flow.