The invention relates to a gamma radiation-resistant polypropylene composite material and a preparation method thereof. The polypropylene composite material comprises the following components in percentage by mass: 60-80% of polypropylene, 5-25% of cis-polybutadiene, and 5-20% of low-density polyethylene. The low density polyethylene is prepared by enabling the polypropylene and the cis-polybutadiene to compound with the low-density polyethylene, and the gamma radiation resistance of the modified polypropylene composite material is relatively high (more than 30KGy).