The invention relates to a method for the measuring axial clearance and the preloading chearance of face-to-face angular contact ball bearings, which comprises the following steps of: first, manufacturing an inner ring spacer bush (4), a gasket (1), an outer diameter loading block (7) and a measuring system; putting the outer ring (3) of a bearing I on the gasket (1); putting the bearing I and a bearing II face to face into the inner ring spacer bush (4), and putting the outer diameter loading block (7) into the outer ring (5) of the bearing II; and calibrating a measuring instrument, and making either end of two equal length levers, which is provided with a right angle measuring head, extend into the measuring instrument through the two gap grooves of the inner ring spacer bush (4). During measurement, the counterweighted outer diameter loading block (7) applies axial loading to the bearing I and the bearing II, two right angle measuring heads respectively align to the central pointsA and B of the bearing I and the bearing II, wherein A-B=delta. If delta is a negative value, the bearing I and the bearing II are shown to be preloading chearance. If delta is a positive valve, the bearing I and the bearing II are shown to be axial clearance. The invention has the characteristic of simple operation. The measuring result does not need complicated conversion. The A valve and the Bvalve can be intuitively read. Besides, conversion and cumulative errors do not exist.