Using density functional theory and non-equilibrium Green's function technique, we investigate the magnetic and quantum transport properties of Tan(B3N3H6)n+1 (n ≤ 4) clusters. The results show that these clusters have sandwich structures as the ground states and their stabilities are all very high, and that the total magnetic moment increases linearly with cluster size increasing. When these sandwich clusters are coupled to Au electrodes, the Au-Tan(B3N3H6)n+1-Au system could exhibit high spin-filter capability under finite bias voltage and can be viewed as a new kind of low-dimensional spin filter.