The invention discloses a device for measuring horizontal displacement of surrounding soil body of a treatment area by using a vacuum preloading method for a laboratory. The device comprises a tank body filled with dredger fill; a vertical draining board and a vacuumizing pipe are embedded into the soil body of a treatment area, are connected with each other, and are connected with a vacuum pump; a sealing film covers the soil body of the treatment area, and the end part of the film is buried, so that negative pressure under the film is formed, and the effective stress of foundation is improved; the sealing film is made from polyvinyl chloride; a loading device is arranged above the sealing film to assist draining; a transverse pipe is inserted into the side face of the tank body, is positioned in the surrounding soil body outside the treatment area, and is sleeved with an annular sensitive source which can be moved along the transverse pipe together with the soil body; a sensor is arranged on the transverse pipe, and is connected with an inductive head; the inductive head can deeply enter the transverse pipe, and can send out a prompt signal when inducing an inductive source, so that different positions of the inductive source at different times can be determined. The device for measuring horizontal displacement of surrounding soil body of a treatment area by using a vacuum preloading method for a laboratory can be used for accurately measuring the horizontal displacement of surrounding soil body when the foundation is treated by vacuum preloading.