We experimentally demonstrate a fiber ring laser for high-resolution torsion measurement,where the laser cavity has a Mach-Zehnder interferometer formed by a pair of long-period fiber gratings written in a twisted single-mode fiber by a CO2 laser.The emitting wavelength of the laser provides a measure of the torsion rate applied to the grating pair,while the direction of the wavelength shift indicates the direction of the applied torsion.The narrow linewidth and the large side-mode suppression ratio of the laser can provide a much more precise measurement of torsion compared with the passive fiber-optic torsion sensors.The achieved torsion sensitivity is 0.084 nm/(rad/m) in the torsion range of ~±100 rad/m,which corresponds to a torsion resolution of 0.12 rad/m,for the wavelength resolution of the optical spectrum analyzer used in our experiments is ~10 pm.