Diffusion bonding of ZrB2 ceramic and Al-Sn-Mg alloys was carried out at atmosphere. The Al-Sn-Mg alloys were Al-xmass%Sn-ymass%Mg (x=0, 0.5, 1.0, 2.0; y=0, 0.5, 1.0, 2.0). ZrB2 ceramic was fine ZrB2 type. The bonding conditions were 873K for 3.6ks, 7.2ks and 14.4ks under the pressure of 1MPa, 2MPa and 4MPa. The microstructures of the bonding interface and the shear fracture surface were investigated by SEM and EPMA. The bonding strength was examined with the shear fracture test. The results show that ZrB2 ceramic could be joined to Al-Sn-Mg alloy with diffusion bonding. “Al-Sn” alloy can be used as an interlayer for diffusion bonding of ZrB2 ceramic. And the optimum “Al-Sn” alloy is Al-0.5Sn-0.5Mg. Shear strength of 42~44 MPa can been obtained for ZrB2/Al-0.5Sn-0.5Mg joint bonded at 873 K for 7.2 ks, 14.4 ks under 2 MPa, 4 MPa.