The invention provides a preparation method of modified rubber and the modified rubber. In the method, high-performance short fibers are irradiated under ultraviolet light to introduce active groups into the high-performance short fibers, and then the high-performance short fibers are modified with a coupling agent so as to increase the compatibility between the high-performance short fibers and a rubber matrix; finally, by means of charge repulsion effect of lauryl sodium sulfate, agglomeration of the high-performance short fibers in the rubber matrix is effectively avoided, which is beneficial to production of the modified rubber. In a bulletproof and puncture-proof tyre produced from the modified rubber, a buffer layer in the tyre is produced with the modified rubber, at least one of a tread, a belted layer and an airtight layer is produced with the modified rubber, and a cord fabric layer of the tyre is produced by weaving twisted high-performance long fibers, so that the tyre has bulletproof and puncture-proof functions, is light in weight and brings stable performance to driving.