Facet evolution and selective area epitaxy of GaAs/AIGaAs ridge and V-groove structure grown on non-planar GaAs(100) substrate by chemical beam epitaxy(CBE) have been investigated for nanostructure applications. To enhance the crystallographic selectivity and to study the new facet evolution on patterned substrate, GaAs and AlGaAs epilayer were grown by growth-interruption mode and continuous mode, respectively. High selectivity of GaAs layer was observed to depend on the various crystallographic planes even at low growth temperature. This was attributed to the efficient Ga surface migration and desorption during the growth-interruption periods. The growth-interruption method was found to be very efficient in improving the morphology of faceted surfaces. We demonstrated that the formation of (111) V-groove and (411) ridge GaAs structures which were surrounded by AlGaAs layer to show the potential implication of this method for the formation of quantum wires.