Duke Cheng of Qin

{{infobox royalty

|name=Duke Cheng of Qin
秦成公

|succession=Ruler of Qin

|reign=663–660 BC

|predecessor=Duke Xuan of Qin

|successor=Duke Mu of Qin

|house=Ying

|dynasty=Qin

|father=Duke De of Qin

|death_date=660 BC

|posthumous name=Duke Cheng (成公)

}}

Duke Cheng of Qin ({{zh|c=秦成公|p=Qín Chéng Gōng}}; died 660 BC), personal name unknown, was the duke of the state of Qin during the Eastern Zhou dynasty from 663 BC to 660 BC.{{cite web |url=http://www.guoxue.com/shibu/24shi/shiji/sj_005.htm |script-title=zh:秦本纪 |trans-title=Annals of Qin |work=Records of the Grand Historian |author=Sima Qian |author-link=Sima Qian |language=Chinese |publisher=guoxue.com |accessdate=1 May 2012}}{{cite book |title=Annotated Shiji |author=Han, Zhaoqi |year=2010 |publisher=Zhonghua Book Company |isbn=978-7-101-07272-3 |language=Chinese |chapter=Annals of Qin |pages=364–365}}

Duke Cheng was the second of the three sons of his father Duke De. His older brother Duke Xuan succeeded his father as ruler of Qin in 676 BC. However, when Duke Xuan died in 664 BC, he passed the throne to Duke Cheng instead of one of his nine sons. When Duke Cheng died four years later, he did the same and passed the throne to the third brother Duke Mu, even though he had seven sons.