The invention provides a detecting device and method for flexibility of a bearing. According to the detecting device, a master controller (3) is connected with a photoelectric counting sensor (6), a rotary speed sensor (15), an electric gripper (19), a drive mechanism (2) and an electric pushing bar (11); the master controller (3) is further connected with a wireless piezoelectricity acceleration sensor (7) through a wireless receiving unit (17). The detecting device and method have the advantages of high detecting precision and efficiency for flexibility of the bearing and low detecting labor cost.