The shroud (or annulus) is installed at the top of the turbine rotor blade, and the lacing is inserted in the middle of the rotor blade to adjust the natural frequency of the rotor blade. After installing the cover ring and tie rod, the stiffness of the blade can be enhanced, the natural vibration frequency of the blade can be improved, and the frequency of the exciting force of steam on the moving blade can be avoided, so that the frequency of the latter does not overlap.