To ensure the seepage stability of earth-rock cofferdam and reduce water seepage,it is necessary to construct cutoff wall inside the cofferdam.High-pressure jet grouting pile is widely used in the cofferdam to reduce seepage because of its fast construction and low cost.Water injection test in borehole and water pressure test in borehole are used in the impermeability testing of high-pressure jet grouting piles.Firstly,the test principle and calculation method for the water injection test in borehole and water pressure test in borehole including constant head and precipitation head are analyzed,and then the high-pressure jet grouting piles with good quality are chosen to carry out the water pressure test in borehole and water injection test in borehole including constant head and precipitation head in the same coring borehole.The results show that the permeability values from three kinds of testing methods are close to each other when the quality of jet grouting pile is good,and the permeability coefficient of water pressure test in borehole is slightly larger than that of full-length water injection test in borehole without difference in magnitude.When there is a leakage point at certain part of the pile,the water pressure test in borehole can find the leakage point efficiently,while it may be difficult for the full-length water injection test to accurately find the leakage point,and the full-length water injection test should not be adopted if the pile is found inhomogeneous from coring.