Canine and feline mesenchymal stem cells（MSCs）have the potential of self ? renewal and multi ? directional differentiation，and are increasingly used in the treatment of pet diseases. In order to ensure the safety and effectiveness of canine and feline MSCs in pet clinical application，it is necessary to meet the clear quality requirements such as basic biological characteristics，biological safety and biological effectiveness. Now the properties of canine and feline MSCs are discussed to provide reference for the establishment of pet stem cell quality control system.