Interferometry is one of effective methods in measurement science. However, due to limited spatial band witdth of detection, it is difficult to increase the dynamic measurement range or to detect high frequency error of surface. The relationship among the spatial frequency and bandwidth of interference fringes and wavefront slope is analyzed and simulated based on the angular spectrum theory. The results show that the maximum slope of interference fringes corresponds to the maximum frequency, and the maximum dynamic range of interference detection can be determined by the wave- front slope, namely the bandwidth interference fringes can be estimated by wave- front slope. Conversely, according to the charge- coupled device (CCD) resolution, the total bandwidth of interference patterns can be determined, then the maximum wave- front slope can be obtained. That provides a theoretical quantitative basis for the spectrum characteristics of the interference methods and optimal allocation of bandwidth.