The invention provides a calibration method and a calibration device of a system for measuring corneal parameters, and particularly the invention provides a system calibration method and device for geometric distortion, caused by camera shooting angle when measuring cornea-related parameters, of a digital slit lamp and a system of similar principles based on machine vision. The method of the invention comprises the steps of: placing a calibration block on a calibration stand, using a slit lamp to shine light perpendicularly to the calibration block, and then photographing in a manner that four vertexes of a cross section are all within a visual range of a digital camera, so as to obtain the four corners and thus corresponding four edges of the cross section； restoring the position of a real image in the image using a ray tracing method； and then performing geometric distortion correction according to real-image coordinates of the four corners in the image and corresponding real-space lengths thereof, thus geometric distortion caused by the camera shooting angle can be eliminated, and the real dimension represented by each pixel can be obtained.
