Snow-melting agent melts the snow on the roads by lowering the snow and ice melting temperature and facilitates road dredging, with obvious effect at the place where it is spread. There are many kinds of snow-melting agents, which can be divided into solid and liquid according to the physical state; they can be divided into inorganic substance and mixture of inorganic substance and organic substance according to the composition, with the latter dominating, in which most of the eco-friendly snow-melting agents are the mixture of the chemicals such as MgCl2- with no or little chlorine; they can also be classified according to different purposes, generally those used for the urban roads are of low quality and those for the places such as the bridges and airports are of high requirements for quality.