Abstract: In order to evaluate the meshing quality of real hypoid gear with cycloid tooth，firstly，the digital gear surfaces that exactly approximate real tooth surfaces are obtained by fitting the measured discrete points with non-uniform rational B-spline (NUＲBS) curve． Then，on the basis of space meshing theory，a tooth contact analysis (TCA) of digital gear surfaces is carried out，which provides contact patterns the same as the traditional rolling test and transmission error curves that can not be obtained from the traditional test． As a result，actual meshing informa-tion can be relatively fully reflected． Finally，the feasibility of the proposed method is verified through a comparison between digital gear surface TCA and rolling test of a high-speed axle gear pair．

Key words: cycloid tooth, hypoid gear, tooth contact analysis, non-uniform rational B-spline