Due to the leakage of frequency spectrum caused by applying fast Fourier transform to the Moiré fringe image, it becomes challenging to achieve accurate 360° full-cycle measurements. A measurement method of full-cycle torsion angle based on Moiré fringe was proposed and a set of torsion angle measurement system was built. The Moiré fringe images with different widths were acquired by a CMOS camera at 1° intervals, and then the grating frequency spectrum information could be obtained by adopting fast Fourier transform (FFT). In addition, the frequency spectrum was corrected by the Hanning-window energy centrobaric method (HnWECM), and the real and effective information of torsion angle represented by Moiré fringe image could be obtained to achieve precision measurement of full-cycle torsion angle. Experimental results show that the system can quickly and accurately realize the full-cycle measurement of the torsion angle with the advantage of wide measurement range, and its maximum error rate is 0.243 3%.