Line 5 of Zhengzhou Metro (Chinese: 郑州地铁5号线; pinyin: zhèngzhōu dìtiě wǔhào xiàn) is a rapid transit line in Zhengzhou that runs in a loop around the city center. It is the only loop-line planned in the Zhengzhou Metro system. The line opened on 20 May 2019. This line is the first rapid transit line to use the "A size" trains in Zhengzhou. "A size" trains are longer and have larger capacity than "B size" trains, which are used on other operational lines of Zhengzhou Metro.