Curvic couplings have been widely applied in industry and almost can be seen in the index table. Following the development of the precision machine industry, except the manufacturing precision, the positioning accuracy is also concerned to meet the demands for curvic couplings. The aim of this thesis is to investigate on manufacturing errors and positioning accuracy of curvic couplings. Discuss the geometric and indexing characteristics of curvic couplings firstly. In the meantime, the new parameter tooth surface of curvic couplings is derived by tooth generating theory. Than, mathematical models are established to simulate curvic couplings at present that are manufactured by grinding machine with different setting errors. Secondly, the practical examples based on the effects of elemental error on the manufacturing error are investigated. Finally, an experimental apparatus is built to measure the actual positioning accuracy of curvic couplings at different input speeds.