Fire security of mosquito-repellent is investigated in this paper with the experiments of several combustibles ignited by mosquito-repellent.The results show that whether mosquito-repellent can ignite combustible matters is related to the types, situations and quantities of combustible matter itself.Mosquito-repellent can ignite materials easily with loose structures, a low flash point, and good heat storing quality, such as paper, sponge and so on.But high polymer materials like wool, chemical fiber fabrics, polyurethane forms and rubber etc.can not be ignited.Tne combustibles with a certaint amount and in dry, loose and fine state have larger capacity of heat storage, and thus are ignited easily by mosquito-repellent, at larger risk of fire.So mosquito-repellent should be kept away from such materials in case of fire.