Based on the first principles, we investigate the structures and electronic properties of fluorinated BC3, BC5, and BC7. Through the fluorination of BC structure, boron-carbon sheets are more stable than the hydrogenation. The results show that the system becomes semiconductor only on condition that the boron atoms can be bonded with the carbon atoms, whereas, the whole system will become the conductor when all atoms participate in the bonding. With the variation of fluorination degrees, semiconductor-metal transitions appear in the BC3 compounds and metal-semiconductor-metal transitions appear in the BC5 and BC7 sheet. Theoretical analyses find that pz orbital of boron atoms plays an important role in the electronic transition. Because of the rich electronic properties, this kind of fluorinated boron-carbon compound will become potential nanoelectronic materials and our results can play a role in guiding experiments.