In order to study the effect of carbon fiber doping on the dynamic compression performance of the grouted body, ultrafine cementitious grouting materials with carbon fiber doping of 0.0%, 0.5%, 1.0%, and 1.5% were used for the grouting test of graded gravels, and the variation rules of dynamic compression strength and energy dissipation of the grouted body specimens were tested by the Hopkinson's Impact (SHPB) test. In order to investigate the microstructure of carbon fibers within the test block, samples were taken from the rupture surface of the test block with optimal fiber doping, and high-precision industrial CT scans and electron microscope scans (SEM) were performed on them. The test results show that: the dynamic compressive strength of the test block with the increase of carbon fiber doping was minus and minus trend, the energy absorption rate was first increasing and then decreasing trend, when the carbon fiber doping of 1% of the best reinforcing effect; carbon fibers in the test block in the approximate normal distribution of the azimuthal angle of the test block is concentrated in the range of 120° ~ 180° and 300° ~ 360° interval, and the polar angle of the test block is concentrated in the range of 60° ~ 90° interval; the carbon fibers are closely bound to the cement hydration product, and the carbon fiber is composed of the carbon fibers, which is the most important part of the cement. The carbon fiber and cement hydration products are closely combined to form a three-dimensional constraint system, which enhances the toughness of the cement matrix, under the action of external forces,the matrix cracks and expands, the carbon fiber plays the role of bridging to hinder the further expansion of the cracks,and the carbon fiber fails or destroys as a result, and its destruction is divided into the de-bonding damage and carbon fiber fracture damage, with the fracture surface of the tension damage being smooth and even, and the fracture surface of the shear damage being 45°. The research results can provide a reference for the in-depth study of the micro failure mechanism of carbon fiber in the grouting body.