Xiao Zhengde (蕭正德) (died 549), courtesy name Gonghe (公和), was an imperial prince and briefly a pretender to the throne of the Chinese Liang Dynasty.
It is not known when Xiao Zhengde was born, but it was known that he was the third son of Xiao Hong (蕭宏), a minor official during Southern Qi and a younger brother of the generals Xiao Yi (蕭懿) and Xiao Yan. As Xiao Yan initially did not have any sons, Xiao Yan adopted Xiao Zhengde to be his own son.
However, in 501, while Xiao Yan was engaged in a civil war against the cruel and arbitrary Southern Qi emperor Xiao Baojuan, Xiao Yan's concubine Ding Lingguang (丁令光) gave birth to a son, Xiao Tong. Despite that, after Xiao Yan overthrew Xiao Baojuan and in 502 forced Xiao Baojuan's brother Emperor He of Southern Qi to yield the throne to him, ending Southern Qi and starting Liang Dynasty (as its Emperor Wu), Xiao Zhengde hoped to be crown prince. Instead, Emperor Wu reversed the adoption and returned Xiao Zhengde to Xiao Hong's line, creating him only the Marquess of Xifeng.
Xiao Zhengde was not at all content with being just a marquess, and he resented the reversal of the adoption. In 522, he fled to rival Northern Wei, claiming to be Liang's deposed crown prince, and sought military assistance. The Northern Wei official Xiao Baoyin, a brother of Xiao Baojuan, instead suggested that Xiao Zhengde be put to death. The Northern Wei government did not kill Xiao Zhengde, but did not treat him with respect. He believed himself to be in danger, and he created a subterfuge—killing a boy and claiming that the boy was his, burying the boy far from the Northern Wei capital Luoyang. In 523, he fled back to Liang. Emperor Wu did not punish him, and in fact restored him to his title and positions.
After Xiao Zhengde's return to Liang, however, he did not regret his actions, but instead gathered thugs, often leading them in robberies. In 525, Xiao Zhengde was a general under the command of Emperor Wu's son Xiao Zong (蕭綜) the Prince of Yuzhang, defending the city of Pengcheng, which was surrendered to Liang by the Northern Wei general Yuan Faseng (元法僧) earlier that year. Xiao Zong, who had long suspected himself to be actually the son of Xiao Baojuan (since his mother Consort Wu was a concubine of Xiao Baojuan and had given birth to him only seven months after becoming Emperor Wu's concubine), defected to Northern Wei during the campaign, and his forces collapsed. Xiao Zhengde abandoned his troops and fled back to the capital Jiankang. Because of crimes he had previously committed and because of his abandoning his forces, Emperor Wu stripped Xiao Zhengde of his title and offices and exiled him to Linhai. However, even before Xiao Zhengde could reach Linhai, Emperor Wu sent a messenger pardoning him and restoring him to his title.