Abstract: An on-line measurement-error correction device and method for the inner profile of a special-shaped shell, including a fixing device. A vertical moving device is fixed at the top of the fixing device and connected with a horizontal moving device connected with a distance monitoring device, which is movable vertically and horizontally under the drive of the vertical and horizontal moving devices. The distance monitoring device includes a displacement monitoring element fixedly arranged on a fixing support hinged with an electric push rod configured to displace to drive the displacement monitoring element to deflect so as to change a monitoring direction. The displacement monitoring element is driven to deflect by the electric push rod of the distance monitoring device to change a monitoring direction, and a distance between each longitudinal section surface point on the inner surface of the special-shaped shell and the displacement monitoring element can be gradually measured.