The utility model provides a string fine adjusting device, comprising a bracket 1, a hooked rod 2 and an adjusting nut 3. The bracket 1 with the concave shape is provided with bow-shaped supporting surfaces 1a and 1b which are right and left symmetry and the middle parts of which are provided with string grooves 4. The bottom surface 1c of the bracket 1 is provided with a circular hole 5 which is provided with a square projecting head 6, and the hooked rod 2 which is matched with the circular hole 5 and is integrated by a string hook 2a with the rod-bending shape and a screw rod 2b which is provided with a long groove 7. The hooked rod 2 can be inserted from the inner side of the bottom surface 1c, and the adjusting nut 3 can be inserted from the screw rod 2b and can be attached tightly at the bottom surface 1c of the bracket 1. Strings 8 can pass through the right and the left string grooves 4 and the string hook 2a on the hooked rod 2, the hooked rod 2 can be moved up-down by rotating the adjusting nut 3, and the strings 8 can proceed with the fine adjustment. The string fine adjusting device has the advantages of simple and reasonable structure and convenient arrangement and operation, and is beneficial to the protection of the strings 8.