Spin-polarized first-principles calculations show that in contrast to pristine boron nitride nanoribbons (BNNRs), the hybrid BNNRs with topological line defects exhibit diverse electronic and magnetic properties. It is interesting to find that with no need for selective edge functionalization, hybrid BNNRs can exhibit half-metallicity and half-semi-metallicity, dependent on the type of edge and line defect. Furthermore, an applied tensile strain can tune the half-semi-metal gap and stabilize the ferromagnetic ordering of the ground state. For hybrid BNNRs with two zigzag edges saturated, the tailoring of line defect state makes the band gap smaller. This work provides a possibility of making spintronic devices based on hybrid BNNRs with line defects and an interesting way of fabricating metal-free half-metal.