This paper investigates the methods for controlling chaos in the Lorenz system with nonlinear control theory. Applying a bang-bang control, we are able to transform the chaotic motion of the Lorenz system to stable motion which may contain apparent short-(or intermediate-) term chaotic motion. In particular, using the control method, we can eliminate the effect of initial conditions on the indeterminateness of the motion and drive the chaotic system to a specified equilibrium state.