Nonunion of flexion-distraction thoracolumbar fractures has few been described previously. The case report discussed a case of nonunion of traumatic lumbar fracture. A 30-year-old man suffered a traumatic L1-2 flexion-distraction fracture and no paraplegia. After complete bed rest 2 months, then hyperextension thoracolumbar cast 3 months, he still felt back pain when out-of-bed activity. X-ray images demonstrated the fracture was not united. At last, the patient underwent open reduction of the fracture nonunion and L1-2 posterior fusion using short segmental pedicle screw instrumentation with autogenous iliac crest graft. The patient gained an excellent functional restoration at 5 months after operation. This suggests that the disease entity may require surgical treatment as early as possible. Spinal fusion combined instrumentation fixation and bone graft may be the best treatment.