The invention discloses a composition for preparing an SEBS/PP blended grafted modification material and a preparation method adopting the same. The composition is prepared from, by mass, 90-100 parts of SEBS, 2-8 parts of MAH and 10-15 parts of PP. The preparation method comprises the steps that 1, all the components in the composition are weighed by mass of parts; 2, the weighed SEBS is subjected to forced air drying under the temperature of 55-65 DEG C for 24 h; 3, the dried SEBS is added into a feeder of a two-screw extruder; 4, the weighed MAH and PP are added into molten SEBS in the two-screw extruder for extrusion, and the two-screw rotating speed of the two-screw extruder is 60-150 rads/min; 5, extrudate is subjected to air cooling and grain-sized dicing to prepare granules; 6, the granules are subjected to radiation treatment by means of cobalt-60 radiation source under the limited oxygen phenomenon, the radiation dosage is 1-50 KGray, and the radiation time is 10-30 min. The SEBS/PP blended grafted modification material prepared through the formula and the preparation method ensures the bonding strength in the SEBS bonding process and also keeps the SEBS transparency.