Spray structure, distribution, and atomization process of the superheated sprays are dramatically influenced by the degree of the fuel superheating. The fuel spray flow field can provide detailed information about such influence due to the fuel superheating. It is anticipated that the fuel spray flow field depends on the superheat degree, which is carefully examined using high-speed PIV in this study. The fuel droplet velocities are measured within the lower number density regions of the spray generated from a multi-hole injector. The spray structure is characterized by spray penetration, maximum spray width and spray angle derived from the spray laser-sheet images. These characteristics are correlated with the spray velocity vector field to analyze the driving force of the spray transformation. The results illustrate that, as the superheat degree increases, the spray velocities in both radial and axial directions vary dramatically accompanied by the unexpected transformations of the spray structure, such as transforming from separate plumes to a collapsed form. The superheat degree is the predominant factor influencing break-up, atomization, and structure of the superheated sprays.