Abstract: Aiming at the problem that the trench of diaphragm wall in the water-rich thick sandy stratum is easy to collapse in grooving for Huanlegu Station of Fuzhou Metro Line 5, different material parameters and construction parameters are designed for strengthening the trench with three-axis mixing pile. The three-axis mixing test in situ and compression test taken core in door are done after 28 days. the variation law of compressive strength of three-axis mixing piles under different material parameters and construction parameters is given out by comparing and analyzing the test results. The optimum material ratio, the amount of cement, quicklime and fly ash for every group of piles are put forward. At the same time the parameters are also put forward about the corresponding falling and lifting speed, the time of staying at the bottom of piles and grouting pressure of strong and weak reinforcement areas. The unconfined compressive strength is not less than 1.0 MPa after 28 days, which ensures the safety of construction on site and provides a reference for similar projects in the future.