At the age of fifteen, Li Chu was made king of Guangping County and married Shen Zhenzhu. During the Anshi Rebellion, he fled to Shu with his father, and persuaded Lingwu to go north after the Maweipo mutiny, serving as the commander of the military forces in the world, commanding the generals to recover the two capitals, and was finally made a prince, leading the troops to quell the Anshi Rebellion.

When Tang Suzong was seriously ill, Li Chu waited on him, and Tang Suzong died soon after. Li Chu later changed his name to Li Yu and became the emperor, namely Tang Daizong. During his reign, he carried out many political and legal reforms, resisted the invasion of Tubo and other foreigners, and gradually restored peace in the Tang Dynasty.