Abstract: In order to study the stability of the hybrid fiber asphalt mixture under high temperature and continuous loading, three kinds of hybrid fiber were selected according to the commonly used fiber and existing research results, and the deformation development and characteristics of internal void structure were experimentally carried out. Firstly, the accelerated loading test was carried out on the mixture of no fiber and three kinds of hybrid fiber under high temperature and continuous loading, cross sectional variation and rutting depth records of different loading times were studied; then the different hybrid fiber mixture void gradation and evolution of void morphology were studied using X-CT scanning technology and three-dimensional reconstruction function of VG software. The results indicate that under high temperature and continuous loading, cross section deformation of hybrid fiber asphalt mixture presents the "W" shape, the different fiber in the mixture plays a "reinforcement", "thickening", "absorbing oil" synergistic effect, the flow deformation of asphalt mixture can be significantly reduced, the flow deformation of the hybrid fiber Ⅲ mixture is the smallest and y=a-b·ln(x + c) can be used to predict the rutting depth of asphalt mixture with different hybrid fibers. After the accelerated loading test, the porosity of the three hybrid fiber increases by only 7%, and the fractal coefficient only decreases by less than 0.5%. Research shows that adding three kinds of hybrid fiber can not change the characteristics of void structure, and under high temperature and continuous loading, the three-dimensional shape characteristics of the internal voids of asphalt mixture can be kept well, in order to improve the anti deformation ability of asphalt mixture.