The influences of a kind of non-periodic force，modeled by bounded noise or chaotic driving，on chaos control of nonlinear dynamical system are studied. Suppressing chaos as well as inducing chaos in a periodically driven Duffing-van der Pol oscillator with 5 nonlinear components is studied in detail. By examining the separation distance，the largest Lyapunov exponent，the scaling exponent of power spectrum, and the Poincar map of the considered oscillator，it is found that the non-periodic driving of appropriate amplitude，on one hand，can eliminate the sensitive dependence on initial conditions，then suppress the chaotic behavior and convert a chaotic attractor to a strange but nonchaotic one in this DVP oscillator. On the other hand，it can induce the chaotic behavior and then convert a periodic attractor to a chaotic one as well. Thus，the dual roles of non-periodic driving，i.e. suppressing and inducing chaos，in chaos control of nonlinear dynamical systems are revealed.