MiR-430 is a non-coding small RNA that participates in early embryonic development by acting on the Nodal signaling pathway. Its functions in Paralichthys olivaceus ( P. olivaceus), however, remain unclear. In this study, through biological information technology, we hypothesized lefty was the target gene of miR-430. Lefty is a divergent member of the transforming growth factor-β (TGF-β) superfamily, and is involved in regulating left-right patterning as an antagonist of the Nodal signaling pathway. To study the relationship between miR-430 and lefty gene, miR-430 and fluorescent expression vector were transfected into embryo cells. Our results showed that miR-430 has important effects on early embryonic development. It can inhibit the expressions of lefty and other genes related to Nodal signaling pathway. Additionally, the expression of miR-430 was involved in the metamorphosis of P. olivaceus. This study clarifies the function of miR-430 in P. olivaceus, which will be helpful for further research on the interactions between miR-430 and the Nodal signaling pathway.