Geminin is a multifunctional protein which localizes in nucleus, it has complicated structural and functional domains. Geminin plays very important roles in cell proliferation, embryonic development, tumorigenesis and so on. Geminin affects cell proliferation through influence on the important events in cell cycle phases. There are many mechanisms by which Geminin can control DNA replication, inhibit centrosome over-duplication, promote G2/M phase progression, maintain proper cytokinesis. At different development stages, Geminin acts as an inhibitor or inducer in regulating embryonic development, especially in nervous system formation. Geminin also plays a regulative role in eye development and embryonic development through the interactions with homeobox genes or proteins Six3 and Hox, Geminin functions as a coordinator of cell proliferative and differentiative control. Recently, Geminin was found to have relationship with cancer, the study on the function of Geminin in cancer has been a meaningful aspect. Geminin can act as a marker to evaluate progression and prognosis in cancer. It may be a novel molecular target in therapy of cancer. The activity of Geminin is regulated by transcription level and post-transcription level, the post-transcriptional regulation of Geminin protein may take the main position.