A device for measuring rotating angles belongs to a device for measuring rotational motion, and solves the problem that large-aperture deep-hole or blind-hole rotating members to be measured are difficult to be mounted and measured by the prior device for measuring the rotating angles. The device comprises a rotating shaft and a measuring flange, wherein, a coniform opening is formed at one end of the rotating shaft, which is fixedly connected with an interfacing flange; a hole type socket connector is mounted on the interfacing flange; a pull claw and a pull rod which are in threaded connection are arranged in the rotating shaft; a digital display screen, an angle sensor, a measuring circuit, a needle type socket connector and a locating cone are mounted on the measuring flange; a pull nail is in threaded connection with the top end of the locating cone which is inserted into the coniform opening of the rotating shaft; and the needle type socket connector is matched with the hole type socket connector. The invention has the advantages the high-precision installation and positioning are realized; and the problem that the large-aperture deep-hole structure to be measured are difficult to be mounted, therefore, the invention is applicable in not only the rotating-angle measurement of deep holes or hermetic cavities, but also the measurement of the relative physical quantity of motion mechanisms such as vibration, swinging and the like.