To address the issues of large shrinkage deformation and low early-age strength of traditional grouting materials, this study prepared a grouting material using ternary composite system (sulphoaluminate cement, Portland cement and gypsum), which featured low shrinkage and high early-age strength. Moreover, the formation mechanism of the microstructure of the obtained grouting material was explored. Results showed that the grouting material prepared according to the optimal mix proportion can exhibit the 1-day and 3-day compressive strengths of 60.1 MPa and 75.5 MPa and 3-day autogenous shrinkage and 28-day drying shrinkage of 351.39×10-6 and 239.75×10-6, respectively, all of which were higher than the national standard requirements. The results of microscopic testing suggested that the ettringite (AFt) in the hydration products of the grouting material overlapped to form a compacted crystal skeleton, resulting in the high early-age strength of the grouting material. At the same time, C-S-H gel in the hydration products promoted the later-age strength development of the grouting material. Furthermore, the micro-expansion effect of AFt gradually reduced the shrinkage deformation of the grouting material, ensuring its high early-age strength and low shrinkage characteristics.