The glucose concentration is one of the main characteristics of solution. Based on the optical rotation effect of glucose solution, motor modulation analyzer, and dual light path simultaneous detection, glucose concentration is obtained from the phase difference of the two modulation signals. Experimental results show that the maximum relative error is about 6.48% with glucose concentration from 0% to 50% (mass fraction). The proposed method solves the problem that rotation angle measurement is limited by mechanical rotation equipment. The measurement equipment has the advantages of simple structure, rapid measurement and strong anti-interference.