In this paper, we consider a class of optimal discrete-valued control problems. Since the range set of the control function is a discrete set and hence not convex. These problems are, in fact, nonlinear combinatorial optimization problems. Using the novel idea of the control parametrization enhancing technique, it is shown that optimal discrete-valued control problems are equivalent to optimal control problems involving a new control function which is piecewise constant with pre-fixed switching points. The transformed problems are essentially optimal parameter selection problems and can hence be readily solved by various existing algorithms. A practical numerical example is solved using the proposed method.