Density functional theory calculations together with periodic slab models are applied to investigate the influence of a ZrO2 support and its surface structures on the stability and nucleation of Pt-n (n = 1-5) clusters. The three surfaces of ZrO2 include cubic ZrO2(c-ZrO2) (111), monoclinic ZrO2(m-ZrO2) (-111), and tetragonal ZrO2(tZrO(2)) (101) surfaces. Our results show that the stability of the Pt-n clusters on the three surfaces and the isolated Pt clusters follows the trend m-ZrO2(-111) > t-ZrO2(101) > cZrO(2)(111) > isolated cluster, whereas the nucleation ability over the three surfaces follows the opposite trend: isolated cluster > c-ZrO2(111) > t-ZrO2(101) > m-ZrO2(-111). Therefore, Pt clusters can have a better stability and dispersion due to the effect of the support.