Abstract: Based on the sliding plane hypothesis of Coulumb's earth pressure theory and the Culmann's graphical construction for the active earth pressure of non-cohesive soil, a new method to calculate the active earth pressure of cohesive soil is derived considering the cohesion force on the sliding surface and the adhesive force on the interface of retaining walls. The assumption of sliding surface for programming is employed to obtain the active earth pressure and the sliding plane angle. Using programming language VB.net design, the procedures are developed. The calculated results show that the proposed method is of simple principle and high precision. It can be easily popularized and applied in projects.