Abstract: This paper introduces the working principle and application method of ground penetrating radar (GPR), and applies GPR to detect the bottom plate of the sluice, showing that the GPR can effectively detect the thickness and safety status of the sluice floor, and the detection process is fast, accurate, and of the advantages with no damages to the sluice. The test results show that the thickness of the bottom plate of the sluice is 1.75 m, the bottom plate is continuous, and there exists small amount of riprap in the upper and lower reaches, and there is no obvious safety hazard.