Nickel hierarchical superstructures have been successfully produced via a simple surfactant-assisted hydrothermal method. The resulting superstructures are formed by the self-assembly of sea urchin-shaped microspheres. Here, poly(vinylpyrrolidone) (PVP) plays an important role in the formation of such structures. A feasible formation mechanism was proposed. The magnetic measurement suggests that the nickel Superstructures exhibit ferromagnetic behavior at room temperature.