Abstract: The development of photocatalytic materials is considered to be one of the effective strategies to alleviate energy shortage and environmental pollution. However, it remains a challenging goal in the field of photocatalysis to simultaneously achieve high efficiency, long-term stability and a wide range of light response. In this paper, BCN/SnO₂ heterojunction were prepared by hydrothermal assisted thermal polymerization of stannic oxide and graphite phase carbon nitride precursor. Results show that BCN/SnO₂ heterojunction has excellent photocatalytic degradation activity, and the degradation rate of methylene blue (MB) can reach 94.8 % when the simulated sunlight irradiation is 40 min. This is due to the synergistic effect of heterostructure and B-doping, which is mainly manifested in the enhancement of visible light absorption characteristics by reducing optical band gap, and the reduction of electron-hole pair recombination, and thus improves the photocatalytic activity. In addition, a model of interfacial band structure of heterojunction was constructed by experiments, the active species and reaction mechanism of photocatalytic degradation were analyzed and discussed in depth.