The invention discloses a fracture reduction assisting instrument, which can perform limb fracture reduction, to overcome some disadvantages of the conventional fracture reduction, improve the work efficiency and medical quality of doctors, and reduce pain of the wounded person. The fracture reduction assisting instrument comprises a support body for mounting a limb fixing device, the limb fixing device for fixing two ends of a fracture site, and a mounting seat for mounting the fracture reduction assisting instrument on a fixed object; the limb fixing device comprises two limb fixing parts, wherein at least one limb fixing part is mounted through a sliding part sliding in a length direction of the support body; the other limb fixing part is mounted through a rotary fixing seat rotating along an axis of a limb. The invention has advantages that the limb fracture reduction assisting device can be use cooperatively with an ordinary X-ray machine; the limb fracture reduction assisting device greatly facilitates the operation of a fracture reduction doctor, saves time and labor, realizes precise reduction, improves the work efficiency and quality, reduces sufferings of patients, and facilitates future follow-up re-examination.