This study introduces a method in analyzing the temporal structure of quasi-periodic oscillations. The idea of the moving spectra will be adopted to study the temporal variation of a time series. The objective of this study is to look at different aspects of the spectral methods in order to detect the periodicity that could be hidden in regular spectra. Results show dramatics changes after applying normalization procedures and statistical tests to the moving spectra. Four idealized cases tested by the moving spectral method reveal that the moving spectral method can transform the time series into the spectral structure.