  Edge structure of graphene has a significant influence on its electronic
properties. However, control over the edge structure of graphene domains on
insulating substrates is still challenging. Here we demonstrate edge control of
graphene domains on hexagonal boron nitride (h-BN) by modifying ratio of
working-gases. Edge directions were determined with the help of both moir\'e
pattern and atomic-resolution image obtained via atomic force microscopy
measurement. It is believed that the variation on graphene edges mainly
attributes to different growth rates of armchair and zigzag edges. This work
demonstrated here points out a potential approach to fabricate graphene ribbons
on h-BN.
