Abstract: A rigid pressure plate method was used to conduct in-situ bearing capacity and deformation tests on the dam foundation of a hydropower station in the Yerqiang River, Xinjiang for a deep and dense sand and gravel covering layer. The tests were conducted using pressure plates with diameters of 50 cm and 75 cm, respectively. The test results showed that the deep and dense sand and gravel layer formed by sedimentation has a relatively high bearing capacity, and no obvious failure characteristics were observed when loaded above 3 MPa, and the proportion limit is not obvious. To determine the characteristic value of its bearing capacity, it is necessary to combine the test curve and S/d value, and consider engineering design for selection. The loading curves obtained from the test using pressure plates with different diameters did not show significant differences, and the deformation modulus obtained was at the same level, indicating that the diameter of the pressure plate has little effect on the test results within a certain scale range.