The soil arch above tunnel face should be considered in the calculation of the minimum support pressure on tunnel face. It is not clear that the effect of water on the soil arch at present. Various model tests are carried out to analyze the differences of the soil arch above tunnel face between dry sand and saturated sand. Tests are performed with a variety of impact factors such as sand particle size, cover depth, and water conditions. Test results showed that the forming process of soil arch is delayed by groundwater and the arch height can be changed. Based on the finite element simulation, it can be concluded that there are two factors which affect the soil arch in water. The first one is groundwater and the other one is internal friction angle. At last, it can be concluded that the lateral earth pressure coefficients of the prism above tunnel face should be revised because the soil arch is affected by groundwater.