The invention discloses a low-temperature-resistant nylon PA66 composite material which is formed by mixing, extruding and granulating a material A and a material B of modified nylon PA66. The invention also discloses an application of the obtained modified nylon PA66 granulated materials to automobile parts. The preparation method mainly comprises the following steps of: adding dried and modified materials into a warmed injection molding machine, setting injection pressure values, injection speed values, injection time values and injection glue amount values of different sections of the injection molding machine, and meanwhile, setting a final dwell pressure value and a final dwell speed value so as to enable the best injection molding technology to be realized, so as to obtain a final qualified product. An automobile plastic connector which is prepared by using the modified nylon PA66 granulated material in an injection molding way is high in impact intensity, good in toughness, is good in flame retardance, and high in low-temperature-resistant performance, and meanwhile, the injection molding technology is stable, the product quality is stable, the percent of pass is high, the production efficiency is improved, and the production cost is reduced.