Objective to investigate the diagnosis and treatment of endochondroma of the left femoral neck with avascular necrosis of the right femoral head and the causes of misdiagnosis. Methods a case of endochondroma misdiagnosed as fibroblastosis was reported and the characteristics of the disease were analyzed. Results the case was diagnosed as endochondroma by pathological examination. Conclusion early abnormal proliferation of bone fibers is similar to the imaging examination of endochondroma of long bone.