The long extension of the Xiao Jiang Fault and its staggered distribution of secondary faults make it difficult for major projects in the region to avoid the impact of active fault zones, therefore, the activity of active faults and site stability are the main engineering stability problems faced by regional major engineering construction. It is of great significance for engineering geological research and disaster prevention and reduction. Methods: In order to find out the effect of active fault on the highway engineering site, based on the geological and tectonic background of the Xiaojiang fault, this paper makes full use of the existing research results, focuses on the regional tectonic environment and fault characteristics, calculates and analyzes the activity rate of the eastern branch of the Xiaojiang fault and determines the degree of fault activity through geological mapping, physical exploration and combined with chronological testing;Taking into account factors such as fault activity, seismic intensity, and rock mass characteristics, the stability of the regional site has been graded. Results: The results show that the average horizontal displacement rate of the Xiao Jiang Fault is 66 mm/a, which is considered as a strong active fault and the stability of the regional engineering site is divided into extremely unstable regions. Conclusions: It is concluded that the impact on the project was most serious in the 10 km area on both sides of the highly active fault, which provides theoretical and data support for site selection and seismic design of highway engineering.