Abstract: In order to comprehend the application of the phaseshift digital interferometry in measurement of optical components, the basic principle of the phaseshift interferometry (PSI) is introduced. The overlapping averaging 4frame algorithm, the configuration of piezoelectric transducer (PZT), the combination method for three PZTs, the correction method for calibration error and nonlinear error of phase shifter, the wave surface phase unwrapping adaptive algorithm, and evaluating specification of wavesurface phase are described. The application of the modern optical interferometry in the measurement of common optical elements, IR optical elements, largeaperture optical elements and aspheric optical components is introduced according to the digital phaseshift wave surface interferometer. It is clearly pointed out that the developing trend of the optical interferometry moves towards high phase resolution, high spatial resolution, wide wave range and highspeed transient measurement, and it will find everincreasing applications in the transient wavefront measurement, microstructure dynamic analysis for micromechanics and so on.