The invention provides a high-temperature polyimide heat-shrink tube and a preparation method thereof. The high-temperature polyimide heat-shrink tube is made from a shape memory random copolymerized polyimide material, and the molecular formula is shown in the specification. The preparation method comprises steps as follows: 1, a diamine mixture solution is prepared; 2, a dianhydride solution is prepared; 3, a polyamide acid solution is prepared; 4, thermal imidization is performed, and a polyimide film is obtained on a glass panel; 5, the film is removed and cleaned, and a random copolymerized polyimide film is obtained; 6, a polyimide heat-shrink tube is prepared; 7, cleaning and drying are performed. The high-temperature heat-shrink tube is prepared in a solvent volatilization manner; the prepared high-temperature heat-shrink tube has an adjustable complete heat shrink temperature in the range from 230 DEG C to 300 DEC C and has wide application prospect in the high-temperature protection field of a sheath and a wire harness of a regional leader cable at the temperature ranging from 230 DEG C to 300 DEG C.