Abstract: DNA double-strand break repair pathway is one of DNA damage repair pathways. DNA repair genes can repair DNA damage, maintain the integrity of the genetic information and inhibit the formation of tumors. There are two mechanisms—non-homologous end joining and homologous recombination to repair DNA double-strand break. In this review, an overview of important repair proteins of non-homologous end joining and homologous recombination pathways was introduced.