Femoral neck fracture, lower 1/3 humerus fracture, lower 1/3 tibia fracture, carpal navicular fracture, lower 1/3 ulna fracture, lumbar isthmus fracture is prone to delayed healing or non-union. Preventive methods: to avoid the formation of a gap between the fracture ends, early reduction of the fracture; gentle manipulation, as far as possible to use non-surgical methods of reduction; fixation is perfect, time is sufficient; strengthen the nutrition, appropriate use of medication; early out of bed activities. Open fractures should also avoid infection. Treatment: fracture end compression therapy, electrical stimulation therapy, application of traditional Chinese medicine and drugs to stimulate bone growth. Once non-healing occurs, i.e. bone non-union, bone grafting should be performed.