Spin tunneling transport properties of two-dimensional electrons through magnetic quantum structures are investigated at zero bias and finite bias. The resultsi ndicate that spin-dependent features are not only related with the magnetic conf iguration, the incident electron energy and the wave-vector, but also closely re lated with the applied bias. At zero bias, the magnetic quantum structure compos ed of identical magnetic-barrier and magnetic-well does not show spin-filtering properties, while the magnetic quantum structure composed of unidentical magneti c-barrier and magnetic-well shows distinct spin-filtering properties. Moreover, the applied bias greatly changes electron spin polarization, which makes the for mer structure also showing interesting spin-dependent features under an applied bias.