A new switched four-scroll hyperchaotic system with two subsystems which are interconnected and can be switched to each other, is generated. The two subsystems are analyzed in detail by presenting the bifurcation diagram, the feature of equilibrium, the phase portraits of chaotic attractor, the Lyapunov exponent and the evolution course of the dynamical action. A practical circuit is designed to conveniently realize two subsystems for the hyperchaotic systems each with only smooth quadratic nonlinearity. Based on time-dependent switching law and state-dependent switching law, the two subsystems can be switched from one to another either randomly or independently, just by using this special circuit.