At the present time, there is a need for effective metrological control of the functional parameters of the modern rotary encoders due to their increased production level. This metrological control has to be carried out with high accuracy and high speed of operation. One of the most effective ways of solving this task is the use of dynamic goniometer (DG) jointly with an optical angle encoder and/or ring laser. The article deals with the principles of DG construction and considers the methods and results of DG investigation for the rotary encoder calibration as well as the elimination procedure of various types of DG uncertainties. The article shows that application of the proposed procedure allows to reduce the level of DG uncertainty to 0.2 arcsec, which ensures the uncertainty value of the rotary encoder metrological control by the means of DG to within 0.05 arcsec in a wide range of angular velocities.