Emperor Yang Yong (楊勇) (died 604), nickname Xiandifa (睍地伐), sometimes known by his posthumous title of Prince of Fangling (房陵王), was a crown prince of the Chinese dynasty Sui Dynasty. He was the oldest son of Emperor Wen and his wife Empress Dugu Qieluo. He drew ire from his parents for wastefulness (which Emperor Wen disliked) and having many concubines (which Empress Dugu disliked), while his younger brother, Yang Guang, whom Emperor Wen and Empress Dugu thought lacked these faults, was favored by them. In 600, Emperor Wen deposed Yang Yong and replaced him with Yang Guang. Subsequently, after Emperor Wen died in 604 (a death that most historians, while acknowledging a lack of conclusive evidence, believed to be a murder ordered by Yang Guang), Yang Guang had Yang Yong put to death.

It is not known when Yang Yong was born. He was the oldest son of Yang Jian and Yang Jian's wife Dugu Qieluo, but it is not known whether he was older or younger than his oldest sister, Yang Lihua (who later became empress to Emperor Xuan of Northern Zhou), born in 561. During Northern Zhou, as Yang Jian's father Yang Zhong (楊忠) the Duke of Sui was an accomplished general, Yang Yong received the title of Marquess of Boping. (This implies, but does not conclusively show, that Yang Yong was born before Yang Zhong's death in 568, when Yang Jian inherited the title of Duke of Sui.) Sometime before 580, Yang Jian and Lady Dugu selected the daughter of the official Yuan Xiaoju (元孝矩), a descendant of Northern Wei's imperial house, to be Yang Yong's wife. During this time, Yang Yong served as a low-level official in Northern Zhou's imperial administration.