Abstract: Objective To investigate the combined effects of low-intensity pulsed ultrasound and low frequency electromagnetic fields in promoting fracture healing. Methods 40 ordinary healthy grown Japanese rabbits were prepared forelegs bilateral radial middle cross-section fracture model and the rabbits werer and only divided into four groups ： Ⅰ _a ，Ⅰ _b and Ⅱ _a ，Ⅱ _b ,each consists of 10.Left side of rabbits from groupⅠ _a and Ⅱ _a was carried combined treatment of the low-intensity pulsedultrasound and low frequency electromagnetic fields（group U），on the right side with only the lowfrequency electromagnetic field therapy（group E） ；Left side of rabbits from groupⅠ _b and Ⅱ _b only for low-intensity pulsed ultrasound therapy（ group B） ，and right side carried out sham treatment as control group（group C） . The intensity of ultrasound treatment is 40mW/cm ² ，20 minutes a day of treatment. The intensity of low frequency electromagnetic field is 0.9mT. 40minutes a day of treatment. X-ray index evaluation of fracture healing was taken after two weeks treatment of groupⅠ _a ，Ⅰ _b and 4weeks treatment of group Ⅱ _a ，Ⅱ _b . Results Semiquantitative analysis of X-ray film evaluation showed that regardless of 2weeks or 4weeks treatment ，fracture healing of group U，B，E are significantly faster than the control group C（P<0.05） ，but no significant difference among group U，B，E（P>0.05） . Conclusion The low-intensity pulsed ultrasound and low frequency electromagnetic fields can promote fracture healing by affecting fracture healing period and modeling period，but the effect of combination of the two treatment to accelerate fracture healing is not obvious.

Key words: low-intensity pulsed ultrasound, low frequency electromagnetic fields, combination treatment, external callus and fracture line