A woman traveling in a train in Huizhou, Guangdong province, with her boyfriend got jealous when the latter started talking to another girl sitting opposite them and told police he was a fugitive.
Police had been searching for Zhuang, who allegedly stabbed and injured a man in early October.
Railway police immediately detained Zhuang after his girlfriend blurted out the truth.
They later handed him over to the local police after confirming he was a wanted suspect.