The present invention discloses a glass fiber reinforced modified polypropylene material and a preparation method thereof, the glass fiber reinforced modified polypropylene material comprises the following components: 20 to 80 parts of glass fiber reinforced polypropylene masterbatch and 20 to 80 parts of glass bead masterbatch; wherein the glass bead masterbatch comprises the following components: 40-70 parts of polypropylene, 20-50 parts of glass beads and 1-10 parts of a grafting compatibility agent. The preparation method is as follows: firstly weighing the polypropylene, the glass beads and the grafting compatibility agent in proportion and mixing evenly for extruding, pulling and pelletizing to obtain the glass bead masterbatch by a twin-screw extruder; mixing the glass bead masterbatch and the glass fiber reinforced polypropylene masterbatch in proportion, using a single-screw injection molding machine for injection to obtain the glass fiber reinforced modified polypropylene material. The glass fiber reinforced modified polypropylene material has the characteristics of high strength, low density, low dielectric constant, low buckling deformation and thermal insulation and the like, and can meet the people requirements of lightweight plastic products; by use of the masterbatch production way, the operation is simple, the complex proportion can be changed according to the performance requirements of the final products, and the glass fiber reinforced modified polypropylene material has high application value and broad application prospects.