The utility model provides two technical schemes for a vibration frequency measuring device. The utility model provides the first scheme that an optical probing unit provided with a light probe is connected with an optical transmission unit made of optical fiber and then connected with a data processing unit; the data processing unit is provided with a photomultiplier module and electrically connected with an optoelectronic pulse counting module; the optoelectronic pulse counting module is electrically connected with a data processing computer; and the light probe serves as a light-incoming end of the optical fiber. The utility model provides the second scheme that the device further comprises a light irradiation unit made up of a laser generator and an optical coupler which are connected together; the light irradiation unit is connected with an optical transmission unit and further connected with an optical probing unit through the optical transmission unit; the optical transmission unit comprises two optical fibers, wherein one optical fiber is connected with a data processing unit, and the other optical fiber is connected with a light irradiation unit; and the light probe of the optical probing unit serves as a light-incoming end made of optical fiber and connected with the data processing unit in the optical transmission unit, and a light-emitting end made of optical fiber and connected with light irradiation unit in the optical transmission unit.