The invention discloses a method and system for on-line detection of roller central axis position changes and a storage medium. The method comprises the following steps that a laser signal of a reference point is acquired, wherein the reference point is arranged on the end face of a shaft head of a roller; the motion track of the reference point is obtained according to the laser signal; and the motion track of a point to be detected is obtained according to the motion track of the reference point and the actual positional relationship between the reference point and the point to be detected,wherein the point to be detected is located at the center of the end face of the shaft head of the roller, and the center of the circle is at the center axis of the roller. The method, the system andthe storage medium solve the technical problem that the roller central axis position changes in the rolling process cannot be detected in real time due to a plurality of detection restrictions in theprior art.