He returned to China to serve as staff officer at the Training Bureau under Yuan Shikai who was then Viceroy of Beiyang.

In 1910 he was dispatched to Urga (present day Ulaanbaatar), Mongolia as the chief of the military staff to train recruits for the Mongolian army.

[4] Recalled to Beijing within a year after complaints from local Mongol officials, he then became the staff officer of Yuan Shikai and upon the establishment of the Republic of China in 1912, Yuan Shikai sent him as one of the Northern Delegates to negotiate with the Nanjing government to effect the unification of the North and the South.

During the first part of 1919 he was Chief Military representative on the Chinese Delegation to the Paris Peace Conference.

[1] Tang returned to China in the summer of 1920 and was made a Jiangjun (General) of the College of Marshals.