The invention discloses an undisturbed soil sample expansion force testing device capable of controlling the saturation. The device comprises a base supporting system, wherein a lower disc is fixed on the base supporting system, a cutting ring base and a cutting ring are arranged on the lower disc, and the upper part of the cutting ring base is provided with an upper cover; a central circular groove and an annular groove are formed on the lower disc, a soil pressure sensor is arranged in the central circular groove, an annular water penetration plate is arranged in the annular groove, water-immersion circular grooves are formed on the annular water penetration plate, water-permeable stones are uniformly placed in the water-immersion circular grooves, and the bottom of the annular groove is connected with an external water injection system through a pipeline; a soil sample is placed between the lower disc and the cutting ring, and a water-permeable plate base which is provided with a water-permeable plate and water-permeable holes is arranged on the top of the soil sample; and a plunger, overflow equipment and vacuum extraction equipment are arranged on the upper cover. The device effectively solves the problems that testing devices for an expansion back pressure method, a pressurization expansion method and a balance pressurization method have relatively large disturbance on soil sample structures, cannot effectively control strict saturation states and are relatively long in testing time consumption.