In order to obtain a polycrystalline yttrium iron garnet ferrite (YIG) joint with both structural reliability and electromagnetic function matching, a new Bi2O3-B2O3-NiO-Fe2O3 glass is designed to fabricate YIG ferrite. The wettability of the glass on the surface of YIG ferrite, typical organization, the impacts of brazing temperature to the microstructure of the joint and mechanical properties is investigated. The result shows that the glass have a well wettability on YIG joint. Some Al was incorporated into the glass solution during melting process and replaced Fe3+ in NiFe2O4 and YFe3B4O12. The growth of NiFe2O4 and YFe3B4O12 is promoted due to the smaller radius of Al3+ and smaller lattice distortion. Small NiFe2O4 particles in the seam transform to large blocky organization as the temperature goes up, proving that high temperature has a positive effect on NiFe2O4 aggregation. The glass-YIG joint has a high shear strength and reaches its maximum of 71 MPa at 750 ℃, then the shear strength decreases with increasing temperature, dropping to 47 MPa at 800 ℃.