The pressuremeter test is a horizontal in-situ load test that can objectively reflect the lateral strength and deformation characteristics of the tested soil. The existing methods for determining the characteristic values of foundation bearing capacity through pressuremeter tests are mainly based on the pressure values corresponding to the starting and ending points of the straight line part of the lateral pressure load deformation curve, which has significant uncertainty. Based on the characteristics of the p-s curve, this article uses a cubic polynomial to fit the p-s curve, and the goodness of fit is greater than 0.99; gives a method for determining the characteristic values of foundation bearing capacity based on the pressure value at the inflection point of the p-s curve; and obtains the bearing capacity of the silty clay layer and the fine sand layer  in the depth range of 46.0 meters. The calculation results show that compared with the near line method, the relative error of the bearing capacity characteristics of the foundation is within 20%, which can meet the engineering needs. This provides a new approach for determining the bearing capacity of foundations through lateral pressure tests.