The invention discloses a lithium battery rolling mill thickness gauge. The lithium battery rolling mill thickness gauge comprises a carbon steel bottom frame and the like. A marble mounting platform is arranged on the carbon steel bottom frame and connected with a linear module, one end of the linear module is connected with a servo motor, the marble mounting platform is connected with a guide roller longitudinal adjusting base, a guide roller transverse adjusting base is connected with the guide roller longitudinal adjusting base, guide rollers are connected with the guide roller transverse adjusting base, the guide rollers are located on the two sides of a marble C-shaped scanning frame, the marble C-shaped scanning frame is connected with the linear module, and a calibration piece, a calibration piece mounting plate and the like are arranged on the left sides of the guide rollers. The human resource cost is reduced, contamination to detection staff is avoided, online automation of detection is achieved, the coverage of measurement is larger, and precision is higher.