The phrase literally means “to beat the retreat-hall drum.” This originates from ancient Chinese government offices or courthouses (衙门, yámén). At the end of a day's session, a drum would be beaten to signal that court was dismissed, and officials could leave. To “beat the retreat drum” yourself, therefore, is to prematurely declare that your own “session”—be it a project, a job, or a commitment—is over. You're calling it quits before reaching the official conclusion.
The imagery of 打退堂鼓 is deeply rooted in China's historical administrative system. The act of beating a drum was official and decisive. Using this metaphor for a personal decision to quit lends it a sense of finality, but also a slightly negative and sometimes self-deprecating tone. In Chinese culture, values like perseverance (坚持, jiānchí) and seeing a task through from beginning to end (有始有终, yǒu shǐ yǒu zhōng) are highly praised. Consequently, 打退堂鼓 is seen as a sign of weakness, unreliability, or a lack of resolve. It's the opposite of the fighting spirit (奋斗精神, fèndòu jīngshén) that is often encouraged. Comparison with “Getting Cold Feet”: While 打退堂鼓 can be translated as “getting cold feet,” there's a key difference. “Getting cold feet” in English is most often used for pre-commitment anxiety, especially before a major life event like a wedding or a public performance. It's about the fear before you take the final plunge. 打退堂鼓, however, typically describes giving up after you have already started. You've begun the work, you've taken the first steps, but when challenges arise, you lose your will to continue. It's less about pre-commitment jitters and more about post-commitment failure of nerve.
This is a very common and informal phrase used in everyday life. It's not typically used in highly formal or written contexts.