An organic polyurethane shape memory material and a preparation method thereof are disclosed. The organic polyurethane shape memory material includes a C10 chain or C18 chain and it consists of hard segment and soft segment. The preparation method thereof includes the steps of:The single-chain type dendrimer reacts with diethylenetriamine to produce multiple chains type dendrimer. And then at least one type dendrimer reacts with N-(3-aminopropyl)diethanolamine to produce at least one type dendritic diols. Next polymer HO(C6H10O2)xC2H4OC2H4(C6H10O2)yOH, x+y=25˜26 reacts with methylenedi-p-phenyl diisocyanate and then at least one type dendritic diols is added to react so as to get organic polyurethane shape memory material. The material of the present invention overcomes shortcoming of metal alloy and ceramic such as poor processability, difficulty in modification and high cost. Moreover, it also increase mechanical properties of polymer.