The invention discloses a preparation method of ionic-bond cross-linked 
polymer vesicles. The preparation method comprises the specific steps of firstly, by taking 
sodium alginate and N-isopropylacrylamide as the major raw materials, and then preparing a temperature and pH value sensitive graft 
copolymer, namely, 
sodium alginate grafted poly-N-isopropylacrylamide through free 
radical polymerization. The graft 
copolymer is prepared into a solution with a certain concentration, and then the solution is mixed with a 
metal ion solution (CaCl2, AlCl3 or SnCl4) different in concentration with the solution under a stirring condition, and the ionic-bond cross-linked 
polymer vesicles are obtained through self-
assembly under the 
electrostatic interaction between negative and positive ions. The preparation method of the 
polymer vesicles is characterized in that the 
metal ions are taken as the cross-linking agent to avoid toxic and side effects caused by chemical cross-linking; the preparation method is mild in preparation conditions, simple and easy to implement; the raw materials are rich in source and non-toxic, and has excellent 
biocompatibility and degradability and further can be taken as a 
drug carrier for therapeutic agents to support drugs different in 
hydrophily and hydrophobicity. The ionic-bond cross-linked polymer vesicles prepared by the preparation method have the particle size in the range from 100 to 350nm and the minimum 
critical phase transformation temperature 
ranging from 34.5 to 38.2 DEG C.