Members of the super-class of zinc finger proteins are key regulators in early embryogenesis. Utilizing in silico mining of EST Databases for pre-implantation Embryo-Specific Zinc Finger Protein Genes, we characterized a novel zygotic mouse gene-tripartite motif family-like 1 (TRIML1), which expresses in embryo before implantation. Knocking down of TRIML1 resulted in the fewer cell number of blastocysts and failture to give rise to neonates after embryo transfer. The binding partner of TRIML1, Ubiquitin-specific protease 5 (USP5), was identified by yeast two-hybrid screening assay. The interaction was confirmed by GST pull-down and coimmunoprecipitation analysis. The role of TRIML1 in ubiquitin pathway during the development stage of mouse blastocyst was further discussed.