Many organic and inorganic compounds have been developed as visible light driven photocatalysts for environment and energy application. In this work, a metal-free carboh doping-carbon nitride (BCM-C3N4) nano composite was synthesized by introducing barbituric acid and cyanuric acid during the polymerization of melamine. The BCM-C3N4 was characterized by structure, porosity, optical performance, and photoelectrochemical properties. Results demonstrated that BCM-C3N4 sample exhibited higher surface area, lower fluorescence intensity, better photocurrent signals and more efficient charge transfer in comparison to pure C3N4. The BCM-C3N4 exhibits excellent photocatalytic degradation ability of sulfamethazine (SMZ) under visible light irradiation. Much superior photocatalytic activity and high pollutant mineralization rate was achieved by BCM-C3N4, where it was 5 times than that of pristine C3N4. The effect of initial SMZ concentrations on photo catalyst was also investigated. Additionally, the trapping experiments and electron spin resonance tests demonstrated that the main active species, such as center dot O-2(-) and h(+), could be produced under light irradiation. This work might provide an effective approach to the design of low-cost and highly efficient photocatalysis degradation systems for water treatment.