Tuberculosis of the long tubular bones in children's extremities is infrequent, particularly in the ulna. Early diagnosis poses significant challenges. This report presents a case involving a 2-year-old child with tuberculosis of the ulnar bone, accompanied by a comprehensive review of pertinent literature. The purpose of this study is to share diagnostic and therapeutic experiences and provide potentially valuable insights. In this case, the patient exhibited complete destruction and expansion of the ulnar bone, resulting in a forearm size considerably greater than normal. Concerns were raised about the irreversible deformation of the ulna, the potential for a malignant bone tumor, and its impact on forearm function, potentially endangering the patient's life. The diagnosis was confirmed as tuberculosis of the ulnar bone. The patient underwent surgery to remove the affected ulnar tissue and received anti-tuberculosis medication. Subsequent to treatment, the destruction and expansion of the ulnar bone resolved, with the return of normal ulnar morphology and bone structure. Even in the absence of typical symptoms like fever, weight loss, and loss of appetite, extensive destruction and expansion of a long tubular bone should prompt vigilant consideration of bone tuberculosis.