The invention relates to a siRNA vector based on a temperature-sensitive cationic polymer and a preparation method of the siRNA vector. The vector has a structural formula as shown in the specification. The amino element of the temperature-sensitive cationic polymer is of a dendritic structure and has high adsorption capacity on siRNA; an alkoxyl ether dendritic element serves as a temperature-sensitive element and has high temperature sensitivity, phase change temperature close to a body temperature and an adjustable temperature-sensitive interval. The polymer controls the binding capacity of siRNA and the amino element by virtue of a phase change process guided by alkoxyl ether dendritic side chains, and the aim of controlling the adsorption and the release of the siRNA by the temperature is achieved. In fact, when the temperature-sensitive performance and the amino element are simultaneously introduced into the siRNA polymer, the vector has important practical application prospects. For example, through the local temperature difference, regional targeted release of drugs and development of intelligent drug vectors applied to gene therapy can be realized.