A novel Al-10Nb-3Ce-2.5B inoculant was prepared, and its effect on microstructures, damping and tensile mechanical properties of Zn-Al eutectoid (ZA22) alloy was systematically studied. It was found that the inoculant had an effective refining effect on the α-phase in the ZA22 alloy (α-phase could be refined to 16 μm), and the morphology of the α-phase could also change from coarse dendrite to small petal. Orientation relationships (ORs) between the α-phase and the CeB₆ and NbB₂ particles in the inoculant were established by the edge-edge matching model (E2EM), and based on the E2EM, the refining mechanism of the inoculant on the ZA22 alloy was revealed. Compared with the uninoculated ZA22 alloy, the high temperature damping of the inoculated ZA22 alloy, especially the damping peak arising from the reverse eutectoid transformation, was significantly improved. Moreover, the room temperature tensile mechanical properties of the inoculated ZA22 alloy were also significantly improved. The tensile strength and elongation of the ZA22 alloy with the best refining effect were 18.56% and 119.04% higher than those of the unrefined ZA22 alloy, respectively. Correlated mechanisms were discussed.