Emperor Ming then welcomed her back from Zhang's house, and the fortunetellers found her to be suitable, and so she was given to Yang Guang in marriage.

Princess Yicheng sent the imperial couple advanced warning of her new husband's plans, and they were able to reach the well-fortified commandery seat at present-day Daixian in Shanxi.

She sent the khan a false report of a northern attack on the khaganate; between this and reports of numerous Chinese reinforcements rushing to answer the emperor's call for help and extravagant promises of reward and promotion, the khan decided to lift the siege and return north.

(Subsequently, though, rather than listening to Xiao Yu's advice to end his campaigns against Goguryeo, Emperor Yang expelled the minister from his court.)

Later, when other ladies in waiting wanted to report on the plot, Empress Xiao advised them against it, reasoning that there was nothing left that could save the dynasty.

In 619, Yuwen Huaji was captured and executed by one of the rebel leaders, Dou Jiande the Prince of Xia.

Dou treated Empress Xiao with kindness and respect while giving a proper mourning for Emperor Yang.

During the years, Tujue's khans continued to use Yang Zhengdao as a magnet to attract the people to surrender, in competition to the Tang dynasty, established by the Sui general Li Yuan (Emperor Gaozu).

In 630, when Emperor Gaozu's son Emperor Taizong of Tang sent the general Li Jing to attack Tujue's Jiali Khan Ashina Duobi, Ashina Duobi's associate Kangsumi (康蘇密) surrendered to Li Jing, taking Empress Xiao and Yang Zhengdao with him.

She died on 17 April 648 in Chang'an and was buried with honors due an empress, at Jiangdu with Emperor Yang.