The invention discloses a mould segment ring (well wall) prefabrication device and a mould segment ring (well wall) prefabrication method, and belongs to the technical field of simulation experimentsof segment rings and well casings. The mould segment ring (well wall) prefabrication device is divided into a pouring device and a mould removal device; and the mould segment ring (well wall) prefabrication device has the removability integrally, and is convenient to operate. The device adopts a low-speed rotating coring method, so that the integrity and the strength of a test sample are protectedto the greatest extent. A mould segment ring (well wall) adopts the prefabrication method, prepared materials are poured into the device for pouring, after natural curing reaches the design strength,mould removal is carried out, and finally the formed segment ring (well wall) is obtained. The device is placed into a similar material of surrounding rock (a soil body), and a novel approach is provided for researching deformation, a broken mechanical mechanism and a structural mechanical characteristic of the segment ring (well wall), and an interactive relationship between the segment ring (well wall) and the surrounding rock (the soil body) in a small similar simulation experiment.