Human diploid cells are the cell matrix for safer vaccine production approved by WHO, and have become the first choice for vaccine production in the world. The diploid KMB17 and 2BS strains independently developed in China are derived from human embryonic lung cells, They have no carcinogenicity, no exogenous factor pollution and relatively stable cell characteristics, more use in human vaccine development and production. Since KMB17 cells and 2BS cells are sensitive to a variety of viruses, they have also been used as cell substrates in the development of many viral vaccines. The vaccines produced by these two kinds of human diploid cells have been widely marketed in China, including hepatitis A vaccine, poliovirus vaccine and inactivated enterovirus 71 vaccine.