In this paper, magneto-electronic properties of zigzag graphene nanoribbons (ZGNR) doped with triangular boron nitride (BN) segments are investigated by using first-principles method based on density functional theory. It is shown that in the nonmagnetic state, the ZGNRs doped with triangular BN segments at different positions are metals. In the ferromagnetic state, with the impurities moving from one edge of the nanoribbon to the other edge, a transition is caused from a spin metal to a spin half-metal, and then to spin semiconductor, and as long as the impurity is not on the edge of the nanoribbon, the doped ZGNR is always spin half-metal. In the antiferromagnetic state, the ZGNR doped in the middle of the nanoribbon is spin metal, while the ZGNR doped on the edge of the nanoribbon has no antiferromagnetic state. The electronic structures of the ZGNRs doped with BN segments at different positions are explained by the difference in charge density. The binding energies of doped ZGNRs are negative, thus the structures of the doped ZGNRs are stable. As the impurity moves from position P1 to position P5, the binding energy decreases gradually. When the impurity is located at position P5, the binding energy of ZGNR is smallest, and the structure of ZGNR is most stable. When the impurity doped in the middle of the nanoribbon, the antiferromagnetic state is the ground state, while the impurity is doped on the edge of the nanoribbon, the ferromagnetic state is the ground state. These obtained results are of significance for developing electronic nanodevices based on graphene.