Abstract: Terzaghi has founded the theory of soil mechanics for nearly a hundred years, but the two most basic problems of soil mechanics are also the most widely used contents of engineering design, calculation of foundation settlement and reasonable determination of bearing capacity, have not been solved very well, so that the soil Mechanics is called a semi-theoretical and semi-experienced "art" science. What is the root of the problem? How to break through? Can the theory be closer to the reality? Here are some of the work and thoughts we have done. The reason why the settlement calculation is not accurate is because the parameters obtained by the indoor soil sample tests are different from those obtained by the in-situ soil tests. At the same time, the usual settlement calculation method is difficult to consider the nonlinear settlement caused by the lateral deformation caused by the soil stress level. The settlement of the foundation is proposed to be calculated by the tangent modulus method established by the in-situ plate loading test on the hard soil foundation, which can solve the problem of in-situ soil parameters and stress nonlinearity, and solve the stress nonlinear problem mainly for soft soils. In order to reasonably determine the bearing capacity of foundation, the load-settlement curve of actual foundation should be calculated, and the bearing capacity of foundations can be reasonably determined only by the load-settlement curve of foundation and the double-control method of strength and deformation. We hope that we can make joint efforts to promote the development of disciplines.