A group of boron-carbon ceramic material was in-situ synthesized and densified simultaneously via Spark Plasma Sintering (SPS) technique from carbon and boron element powders with different molar ratio. The phase structures of samples with different B/C molar ratio were characterized by X-ray Diffraction (XRD). The B/C atomic ratio of the sintered materials was calculated from X-ray photoelectron spectroscopy (XPS) measurement data. Meanwhile, the chemical analysis (CA) method had also been taken to verify the B/C atomic ratio. Finally, the experience equation had been obtained to control the B/C atomic ratio of sintered samples.