Mesenchymal stem cells are a kind of non-hematopoietic adult stem cells with selfrenewal and multilineage differentiation potential, which have special biological characteristics, such as secreting hematopoietic growth factors, reconstructing hematopoietic microenvironment, low immunogenicity, and can be transfected and expressed by exogenous gene. This article summarizes the biological characteristics of MSCs and their models of application to acute radiation disease in animals.