RNA polymerase is responsible for RNA biosynthesis and is an important regulatory machine for maintaining cell growth and organ development. Eukaryotes mainly transcribe genes through three kinds of multi-subunit RNA polymerase (RNAPⅠ, RNAPⅡ and RNAPⅢ). RNA polymeraseⅡ consists of 10 core subunits, the molecular size of which is about 520 ku. Structure and function of RNA polymerases have been clarified, but their assembly process are not clear. RNA polymerase subunits can not be completely self-assembled in vitro, indicating that this process in cells needs the help of assembly factors. RNA polymerase assembly is a complex biological process. In recent years, the identification and functional analysis of assembly factors have made RNA polymerase assembly a hot spot. The assembly factors found in Saccharomyces cerevisiae are Rba50, Bud27 and GPN protein family. Among them, GPN protein family is an important GTPase family, which exists in archaea, yeast and higher eukaryotes, and is highly conserved. Recent studies have found that Rba50 homologous proteins (IYO and RPAP1) in plants and animals are related to cell differentiation and tissue development. Mutations in assembly factors such as GPNs are closely related to cell development and cancer development. This article reviews the latest progress of RNA polymerase assembly in eukaryotes, with a view to provide a basis for the final elucidation of RNA polymerase assembly mechanism and its association with disease occurrence.