The structural stability, electronic structure, and optical properties of BN-doped black phosphorene systems at different concentrations were investigated using a density generalized theory approach based on the rst principles. It was found that BN-doped black phosphorene was more stable compared with B and N atom doping. With the increase of doping concentration, the stability of the structure gradually decreases, and the structure of the system with 25% doping concentration is the most stable. The intrinsic and N-doped black phosphorene are direct bandgap semiconductors, and B and BN doping make the black phosphorene change from direct bandgap to indirect bandgap. The total density of states is mainly contributed by the p-state electrons of the B and P atoms, and the N atoms have a role in the local density of states with little contribution to the overall one. The black phosphorene undergoes charge transfer between the B and N atoms. The amount of charge transfer increases with the increase of doping concentration. The BN-doped black phosphorene system is blue-shifted at the absorption and re ection peaks compared to the intrinsic black phosphorene system. The doping makes the dielectric function peaks are shifted to the high energy direction, which leads to an increase in the intensity of the electric eld generated by light, which is bene cial to improve the e ciency of photovoltaic power generation, and the peak of photoconductivity is slightly reduced and shifted to the low energy direction, which is more favorable to the leap of photons, with the most obvious performance when the BN doping concentration is 12.5% and 25%.