Histone lysine crotonylation is a non-acetyl histone lysine modification that is evolutionarily conserved. It plays an important role in regulating various biological processes, including gene transcriptional regulation, spermatogenesis, and cell cycle. However, the dynamic changes and functions of histone crotonylation in preimplantation embryonic development in mammals remain unclear. In this study, we have shown that the transcription coactivator P300 functions as a writer of histone crotonylation during embryonic development. Depletion of P300 resulted in significant developmental defects and dysregulation of the transcriptome of embryos. Importantly, we demonstrated that P300 catalyzes the crotonylation of histone, directly stimulating transcription and regulating gene expression, thereby ensuring successful embryo development to the blastocyst stage. Furthermore, it is showed that the histone H3 lysine 18 crotonylation (H3K18cr) modification is predominantly located in active promoter regions. It serves as an epigenetic hallmark of key transcriptional regulators and promotes the transcription activation of genes. Together, our results propose a model wherein P300-mediated histone crotonylation plays a crucial role in regulating the fate of embryonic development. Overall design: Comparative gene expression profiling analysis of RNA-seq data for preimplantation mouse embryos between the control group and the P300 knockdown group at three distinct developmental stages. Additionally, gene expression profiles comparative analysis of preimplantation mouse embryos from the control group, P300 knockdown group, and two rescue groups at the late 8-cell stage.