Killian-Jamieson and Zenker diverticula are both rare pharyngoesophageal diverticula. Both are outpouching of the mucosal and submucosal layers of the esophageal wall, which protrude through a mucosal gap at the level of the pharyngoesophageal esophagus. When these diverticula are large enough, they can be in proximity to the thyroid gland and may mimic a thyroid nodule. We report a case in which a diverticulum was filled with dietary residue and thus simulated a thyroid cyst on CT scan. And it was finally diagnosed as a Killian-Jamieson diverticulum by the surgery.