离乡背井（離鄉背井）　

◎ 离乡背井 líxiāng-bèijǐng

[flee one‘s home;tear oneself away from one’s native place; turn one‘s back on one‘s native land and leave it] 离开家乡去谋生

大批农民离乡背井,去寻找新的肥沃土地