The zhu (筑; pinyin: zhú) was an ancient Chinese string instrument. Although it is no longer used, three very old specimens in varying degrees of preservation survive. One with five strings, dating to approximately 433 BC, was discovered in the Tomb of Marquis Yi of Zeng, in the Hubei province of central China.
The instrument remained popular through the Sui and Tang dynasties, and was lost during the Song Dynasty.
Little is known about the instrument but it is believed to have been a zither with a rectangular wooden body, with silk or gut strings that were played with a slender stick. Although ancient sources state that the instrument was struck (implying that the stick was bounced on the string in the manner of a hammered dulcimer in order to elicit sound), it is possible that it was actually plucked with the stick in the manner of the Korean komungo.