A grouting material using ternary composite system including sulphoaluminate cement， Portland cement and gypsum was prepared， which featured low shrinkage and early strength. The formation mechanism of the microstructure of the obtained grouting material was explored. The results show that the grouting material prepared according to the optimal mix proportion exhibits 1 d and 3 d compressive strengths of 60.1 MPa and 75.5 MPa， and 3 d autogenous shrinkage and 28 d drying shrinkage of 351.39×10^-6 and 239.75×10^-6， respectively. All of them are higher than those of national standard requirements. Ettringite（AFt） crystals in the hydration products of the grouting material overlap to form a compacted network skeleton， resulting in the high early strength of the grouting material. At the same time， calcium silicate hydrate gel in the hydration products promotes the later strength development of the grouting material. Furthermore， the micro-expansion effect of AFt gradually reduces the shrinkage deformation of the grouting material， ensuring its early strength and low shrinkage characteristics.