In order to measure the optical rotation angle of glucose solution and sucrose solution, a rotating waveplate polarimeter is established. The polarimeter is full fiber system and uses the fiber taper to probe the optical rotation of liquid. First, through the establishment of system equations, squares optimization is used to estimate the Mueller matrix of the solution under test, and then, using the Mueller matrix decomposition to calculate the optical rotation angle of the sugar solution. Then, the optical rotation angles of glucose and sucrose solution at different concentration are measured by the experiment system. Results show that optical rotation angle linear increase with the increase of concentration of glucose and sucrose solution. Compared to the traditional measurement of optical rotation angel, the systematic polarization alignment is not necessary in our system. Consequently, the experimental operation is simple, and then the features make the system quite remote and feasible. It can satisfy the system requirements of higher precision.