The invention relates to an experimental method for a flexible retaining wall soil pressure model. The experimental method comprises the specific steps that a teaching experimental system is manuallymounted, wherein the experimental system comprises a retaining wall model system, a displacement and soil pressure data acquisition system and a synchronous control system; soil samples are manually filled and compacted; the synchronous control system is operated to measure the change of the oil pressure of all parts of the wall back and soil displacement in real time while controlling movement ofa retaining wall model; and according to a sliding breaking surface generated by soil, a soil pressure calculation model is established, and a theoretical formula is deduced. According to the experimental method, equipment automatic control can be achieved, operation is convenient, the time and materials are saved, and the experimental efficiency is improved; various flexible retaining wall formsand displacement modes can be simulated; the change condition of a soil displacement field can be intuitively observed through a PIV system; the synchronous relation between the systems is established, and the change condition of the wall back soil pressure and soil displacement distribution of a flexible retaining wall in complex deformation and displacement processes can be observed synchronously; and the development and change processes of a soil plastic area behind the flexible retaining wall can be observed in real time.