The electronic structure of graphene and hexagonal boron nitrogen (G/h-BN) systems have been carefully investigated using the pseudo-potential plane-wave within density functional theory (DFT) framework. We find that the stacking geometries and interlayer distances significantly affect the electronic structure of G/h-BN systems. By studying four stacking geometries, we conclude that the monolayer G/h-BN systems should possess metallic electronic properties. The monolayer G/h-BN systems can be transited from metallicity to semiconductor by increasing h-BN layers. It reveals that the alteration of interlayer distances 2.50–3.50 Å can obtain the metal–semiconductor–semimetal variation and a tunable band gap for G/h-BN composite systems. The band dispersion along [Formula: see text]–[Formula: see text] direction is analogous to the band of rhombohedral graphite when the G/h-BN systems are semiconducting.