Lu Chengqing was born in 595, during the reign of Emperor Wen of Sui. He was from "The elder house of northern ancestry" (北祖大房) of the prominent Lu clan of Fanyang. His grandfather Lu Sidao was an important official during the Sui dynasty. Late in the reign of Emperor Wen's son Emperor Yang, Lu Chengqing's father Lu Chisong (盧赤松) was serving as the magistrate of Hedong County (河東, in modern Yuncheng, Shanxi), when the general Li Yuan rebelled against Emperor Yang's rule at Taiyuan. Lu Chisong, who had previously known Li Yuan, surrendered as soon as Li Yuan's forces arrived and served on Li Yuan's staff. After Li Yuan established the Tang dynasty as its Emperor Gaozu, he created Lu Chisong the Duke of Fanyang. Lu Chengqing was said to be handsome and attentive to his appearance, but also knowledgeable and capable. When he was young, Lu Chisong died, and so he inherited the title of Duke of Fanyang.
