Dual rotating retarder configuration is applied in measurement system,whose incident and scattering light are modulated by synchronously rotating two quarter waveplates. From the 25 Fourier coefficients measured by performing Fourier decomposition of the signal,the 16 elements of sample's Mueller matrix are determined. We compare the experiment data of air with the ideal matrix to check the accuracy of measurement system,and present the standard error of each Mueller matrix element. Finally,the depolarization of polytetrafluoroethylene sample is analyzed quantitatively by the measured Mueller matrix.