In late 1969, the 13-year-old Jin lied about his age and joined the People's Liberation Army. He was assigned to a border defense unit and stationed in a village called Guanmenzui, where most of the residents were ethnically Korean.
1969 年末，14 歲未滿時他便虛報年齡加入解放軍，屬邊防團，曾駐守在一個叫做關門嘴的村子，村民多是朝鮮族。