Bearing unit clearance is a key indicator that affects the fatigue life of products; an excessive or undersized clearance will lead to a short bearing life. Wheel bearing clearance can be divided into the state of assembly clearance and loading clearance, the final working clearance is at loaded state. Unloaded wheel bearing clearance is called the assembly state clearance, when the bearing in this state is loaded, it will be locked by a specific torque of the wheel axle bolt and produce an axial locking force, which causes the axial deformation of the raceway. So the assembly clearance will be changed and form the loading clearance, also known as working clearance. In order to obtain the working clearance of the wheel bearing, the axial locking force (referred to as the axial force) of the wheel bolt under certain torque is required to be tested and obtained on the basis of ensuring that the assembly clearance meets with the design requirements. At present, there are some disadvantages in the applied axial force test method. The fasteners manufacturers generally consider the fasteners as the main test object, be-fasteners are replaced by tooling to implement the test, which will inevitably result in distortion of the friction coefficient between the nut joint face and affect the accuracy of the results. There are two ways to install the test elements: one is to embed the sensor into the wheel bolt, and the other is to affix the sensitive element to the machined surface of the bolt. The two testing methods are limited because of the particularity of the structural characteristics of the wheel axle bolts. This study is to construct an axial force test system for wheel bearing, which will provide the test basis for ensuring the highly working life of working clearance for wheel bearing.