A system for measuring the rotation angle of optical active substances (15) has a light source (10), a polarization generation unit (11), a polarization analyzing unit (12), a signal generating unit (13), respectively and electrically coupled to the polarization generation unit (11) and the polarization analyzing unit (12), a signal processing unit (14), electrically coupled to the electric signal generating unit (13), wherein the light source (10) is enabled to emit a beam (100) toward the polarization generation unit (11) for enabling the beam (100) to be polarized into an incident polarized beam (110) while being projected and travelled in an optical path passing through an optical active substance (15) so as to be converted into a emerging beam (150) and the polarization analyzing unit (12) is positioned to receive and analyze the emerging beam (150) so as to generate a signal to be received and processed by the signal processing unit (14).
