By numerically integrating the one dimensional time dependent SchrAo¨Gdinger equation, the ionization and high harmonic generation of a model atom submitted to two color laser fields are investigated. By considering two different ionization mechanisms: the tunneling ionization regime and the over the barrier ionization regime, it is found that the ionization behaviors are quite similar, while the high harmonic generation behaviors are very different. The results demonstrate the possibility of phase control of atomic processes by using two color fields.