Abstract: The application of phaseshifting interferometers for measuring angles of the cone cube reflectors (CCR) is studied so as to realize the realtime and high accuracy test for optical elements. The relationship between the dihedral angle errors of CCRs and the interference pattern is obtained by calculating the dihedral angle errors of CCRs. The relationship between the shape of interference wavefront and the synthetic errors of CCRs is analyzed. A program to test the dihedral angle errors and the synthetic errors of CCRs is designed. After lots of experiments and comparison of the results by the digital phaseshifting interferometer and the ZYGO interferometer, it is proved that, in the program of CCR test, the measurement error of the dihedral angular difference is less than 0.3″ and the measurement error of RMS is in λ/50 with the application of digital phaseshifting interferometer.