The invention provides a star-shaped isoprene-styrene copolymer containing a random transition section and a preparation method thereof. The star-shaped isoprene-styrene copolymer is characterized in that the structural formula is [I1-S1-I2/S2]n-Y,], wherein Y is Si or Sn, n is a branching degree, n is more than or equal to 2.5 and less than or equal to 4, and I1-S1 is a transition section copolymer of polystyrene and polyisoprene; I2/S2 is a random section copolymer of the polystyrene and the polyisoprene, the mass fractions of transition sections of the polystyrene and the polyisoprene are 40-75wt%, and the mass fractions of random sections of the polystyrene and the polyisoprene are 25-60wt%. High styrene rubber disclosed by the invention has the characteristics of high hardness and good intensity and elasticity; when the high styrene rubber is used simultaneously with multiple synthetic rubber or natural rubber, the properties of rigidity, hardness, wearing resistance, tear resistance, dielectricity and the like of rubber products can be improved, and the high styrene rubber can be widely applied to the rubber processing fields of tires, tapes, rubber tubes, rubber overshoes and the like and other industries and can be further used for modifying synthetic plastics.