The invention discloses a fracture simulation adjusting mechanism of a grouting expansion testing device, and belongs to the technical field of grouting expansion testing equipment. The fracture simulation adjusting mechanism comprises adjusting parts and measuring parts, wherein the adjusting parts comprise a fastening screw nut, an adjusting bolt, an upper pressing plate, a visible plate, a lower pressing plate, a bottom plate, a gland and a servo motor; the fastening screw nut is fixed on the upper pressing plate; one end of the adjusting bolt is connected with the fastening screw nut; the other end of the adjusting bolt is connected with the servo motor; the gland is fixedly connected with the bottom plate; the measuring components comprise a displacement measuring rod and a displacement sensor; the displacement measuring rod is arranged inside the adjusting bolt; a first sealing ring is arranged on the displacement measuring rod; a second sealing ring is arranged on the adjusting bolt; a spring is mounted on the displacement measuring rod; the displacement sensor is connected with the servo motor. By adoption of the fracture simulation adjusting mechanism, multiple functions of balancing inner pressure, adjusting fracture width and measuring width are achieved, accurate basis can be provided for grouting construction and establishment of slurry expansion models, and the grouting effect can be ensured.