Abstract: Polypropylene is widely used because of its excellent performance in many fields, but also has some defects such as poor toughness, poor melt strength. The high melt strength polypropylene which has high melt strength, melt elasticity, has been focus of the research on polyolefin over the years. It is found that expand the polypropylene in the physical foaming, extrusion coating and thermoforming, and other fields of application. In this paper, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane as the initiator, a multi-functional monomer trimethylolpropane triacrylate was grafted with commercially polypropylene, while adding a branching accelerators tetrabutyl thiuram disulfide to improve grafting efficiency. The high melt strength polypropylene is successfully prepared and its recipe is optimized. In this paper,The melt flow rate of grafted product are determined and its melt strength is calculated by formula method. By infrared spectroscopy, the molecular structure of the high melt strength polypropyleneare analyzed and characterized，and the result showed the monomer has been grafted onto the main chain of polypropylene. By differential scanning calorimetry, thermal gravimetric analysis method, thermal properties of the high melt strength polypropylene are analyzed and characterized. The results showed that the melting temperature of the grafting products were not significantly change, and heat temperature has increased.The mechanical properties measurement results such as tensile strength, bending strength, impact strength, show that the mechanical properties of grafted products have improved significantly.