The modified asphalt used in the Drainage Pavement generally adopts the wet process, and the wet modified asphalt has good performance. However, with the application of wet modified asphalt, modified asphalt is faced with some problems, such as easy segregation, high cost and difficult quality control. The application of direct feed modifier is a dry process. It is first mixed with aggregate, and then asphalt and other materials are added to prepare asphalt mixture. The application of direct injected modifier avoids the shortcomings brought about by wet process. In this study, direct injected high viscosity direct injected modifier with excellent performance in all aspects is selected for plant mixing of asphalt mixture by dry process, including the impact of dry mixing time and dry mixing temperature on the performance of mixture in indoor mixing, so as to guide the determination of plant mixing dry process. The asphalt mixture in the test project is selected for sampling analysis to study the difference between the performance of the mixture prepared by the plant mixing dry process and the performance of the indoor mixture.