The deducation of analytic solutions for 3D slope stability analysis is the difficult problem in the anea of geotechnical Engineering.Based on the stress analysis of a point in space， the stress analysis of a point on a surface is performed， and then the relationship among the normal stress， the shear stress，the stress component of a point on a surface and the first order partial derivative of the surface equation is deduced. Equilibrium equations of soil columns between the sliding surface and the top surface of the slope are established， which include differential equilibrium equation of force， equilibrium equation of force， and equilibrium equation of moment. These equilibrium equations and Coulomb yield condition can form the fundamental equations of three-dimensional slope stability analysis. Applying the supposition similar to that applied in the simplified Bishop method， a kind of three-dimensional slope analysis method can be obtained. An example is presented to show that the computation method is reasonable and applicable，which provides significance for the further deducation and application.