The effective doping of semiconductor materials can guarantee the successful application of semiconductor devices. Theoretically, the difficulty of doping and the depth of defect level can be predicted by calculating the defect formation energy and charge transition energy level. The defect properties of four potential substitutional n-doping systems (CB, SiB, GeB,SnB,) in two-dimensional (2D) BN were systematically calculated based on density functional theory and combined with two-dimensional charged defect calculation method. The results show that the most stable valence states of CB(SnB) system are +1(-1) and 0 valence, while the most stable valence states of SiB and GeB system are +1, 0 and -1 valence. The corresponding donor ionization energies of CB, SiB and GeB systems are 2.00 eV, 3.57 eV and 4.06 eV, they all show deep level donors, and it is difficult to provide n-type carriers for h-BN. In addition, in p-type doped host h-BN, CB system has negative formation energy and +1 valence, which will seriously reduce the p-type doping efficiency and hole conductivity of h-BN. The results provide a theoretical basis for experimental doping of 2D h-BN.