During vertebrate embryonic development, the body axis formation requires action of wnt signals and their antagonists. Zygotic canonical wnt8 expression appears exclusively at the ventrolateral margin and mediates Wnt/beta-catenin activities to promote posterior and ventral cell fate. However, the mechanisms involved in the initiation of zygotic wnt8 signals are completely unknown. Here we identify a novel maternal derived transcriptional factor, Kaiso zinc finger containing protein (KZP), is an important determinant for the initiation of zygotic wnt signal in zebrafish. We demonstrated that KZP recognized specific consensus sequences and bound directly to wnt8 promoter to control the initiation of wnt8 expression. Depletion of KZP strongly dorsalized embryos characterized by the expansion of dorsal genes expression while overexpression caused posteriorization, which phenocopied wnt8 depletion or overexpression phenotypes and can be rescued by alternation of wnt8 activity. Thus, our results provided the first insight into the mechanism involved in the initiation of zygotic canonical wnt signal by maternal derived factor.