Duke Ding of Qi (Chinese: 齊丁公; pinyin: Qí Dīng Gōng; reigned c. 10th century BC) was the second recorded ruler of the ancient Chinese state of Qi during the Western Zhou Dynasty. His personal name was Lü Ji (呂伋) and ancestral name was Jiang (姜). After Duke Ding died, he was succeeded by his son Duke Yǐ of Qi.