The invention belongs to the technical field of measurement of the axial play of bearings, and relates to a measuring method and measuring device aiming at the axial play of four-row tapered roller bearings. The measuring device is mainly composed of an adjusting device, an inner ring clamping device, an outer ring loading device and a play measuring device. By adjusting the position of a threadedguide rod relative to a guide sleeve, clamping of different inner rings is achieved; through the loading device, loading of different rows of rollers is achieved. The measurement of the axial play oforiginal four-row tapered roller bearings is equivalently converted into the measurement of the axial play of three sets of two-row tapered roller bearings ingeniously, the measuring method is simpleand easy to operate, self-locking of rollers is avoided, during measurement, turning is not needed, the method can be implemented through automated equipment, and the measuring efficiency and the measuring precision are greatly improved.