Three-stage Mueller matrices measurement by polarization state modulators is presented theoretically, and the method is verified by experiment. Through the establishment of system equations, the Mueller matrices of optical device under test can be solved by least squares algorithm. The scheme which is based on system estimation theory is different from the method of measuring the input/output states of polarization with an in-line polarization state analyzer. The Mueller matrices and physical polarization parameters can be obtained in just one experiment. The standard deviations of measured retardances of optical components are 0.0012, 0.0018 and 0.0040, respectively. In addition, the simulation of uncertainty and the error accumulation of the system are discussed in detail. There is error accumulation effect in the cascaded system, and the result is consistent with the experimental data.