Abstract Based on Green’s function method, we investigate spin-dependent transport properties of a double bend quantum wire. It is found that a notable spin polarization can be achieved in a broad energy range when magnetic field and Rashba spin-orbit coupling (RSOC) only exist in the intersection of two quantum wires. The strength of RSOC and magnetic field has drastic influence on the spin polarization. The amplitude of spin polarization can be tuned from 0% to 100% by adjusting RSOC or magnetic field. In addition, the effect of geometric size on the spin polarization is discussed. The results show that the double bend quantum wire may be employed for spin filter.