The present invention belongs to the field of optical detection devices, and especially relates to a polarization modulation structure and a polarization measurement system. The polarization modulation structure comprises a rotation compensator and a polarizer, the rotation compensator is a continuously rotated composite wave plate formed by combination of a plurality of single wave plates with the same materials, and the whole structure of the composite wave plate is optimally designed and determined by employing thickness of each single wave plate and an inclined angle of an optical axis according to a polarization property transmission matrix. The polarization modulation structure is simple in structure, easy to process and wide in wavelength application range, a broadband polarizationmeasurement system is designed based on the polarization modulation structure, and therefore, the polarization modulation structure and the polarization measurement system are suitable for the demandsof the broadband precision polarization measurement.