Abstract: The detailed data shows us that in the first year of the Daye period (ie. 605 BC)of the Sui Dynasty, just the year when Emperor Yang took his position, he initiated several giant public projects including the Great Canal; and as soon as the southern section of the Great Canal was completed, Emperor Yang, together with his wives and officials, made an inspection tour of Jiangdu, which, in the old historical books and novels, has been said to be simply a royal sightseeing tour just for an amusement. But on the basis of the data, the author argues that this tour had propel a political and cultural communication between the South and the North and made a contribution to unification of the country. So it has a profound significance in strengthening the political unity. However, it cost too much and led to the unbearable people to overturn the Sui Dynasty.