Through reviewing research advances on promyelocytic leukemia(PML) protein at home and abroad in recent years, the authors summarized the biological functions of PML protein in this paper. Recent researches indicated that all PML protein isoforms have RBCC (Ring finger domain, B-box, Coiled-Coil domain, RBCC)or TRIM (TRIpartite motif). There was a close relationship between the three SUMO-1 (small ubiquitin-related modifier, SUMO-1) modification site of PML protein and its location in nuclear bodies (NBs). Moreover, the location of PML protein in NBs is very important for the exertion of the function of PML protein and the formation of NBs. PML protein possesses multiple biological functions, such as intrinsic antiviral activities, suppressing the growth of tumor, participating in the differentiation of hemopoietic progenitor, regulating transcription of genes, inducing cell apoptosis, and so on. The PML gene haploinsufficiency and the formation of PML-RARalpha fusion protein are not only the pathogenesis of APL but also the target of treatment.