As germ cell precursor, primordial germ cells (PGCs) are widely used in transgenic animal production, regenerative medicine and other fields. However, the regulation mechanism of chicken PGCs is not incomplete, which leads to the insufficient amount of chicken PGCs obtained in vitro, which seriously affects the specific application of PGCs. During PGC formation (differentiation from ESCs to PGCs), some proteins have inconsistent changes in transcription level and protein abundance. Mediating proteasome degradation is one of the most important roles of protein ubiquitination, and enrichment analysis of transcriptome and proteome also suggests an important role of ubiquitination in the process of PGCs. In order to explore the important functions and potential targets of ubiquitination, we collected chicken ESCs and PGCs cells for label free ubiquitomics analysis. This study preliminarily analyzed how ubiquitination regulates the formation of chicken PGCs, providing a theoretical basis for the subsequent research and specific application of PGCs.