In order to understand the characteristics of large section water-rich loose sandstone tunnel pre-strengthened by horizontal jet grouting pile, taking Shaojiatang tunnel of Qingshuiyi to Zhonghe section of G30 Lianhuo Expressway as the engineering background, model tests were carried out to study the large section water-rich loose sandstone tunnel pre-strengthened by horizontal jet grouting pile. The results show that the vertical displacement is mainly concentrated on the top of the arch, there is no obvious arch bottom uplift and the horizontal displacement is not obvious. The horizontal jet grouting pile plays an obvious role in controlling the seepage flow of surrounding rock at the arch waist. The stress state of surrounding rock is three-way compression state at measuring points 6, 7 and 8, unidirectional tension and unidirectional compression state at measuring points 4 and 12, and the rest are three-way tension state.