Following graduation, Yuan-liang Sun entered Army service and fought many battles for the Revolution, being seriously wounded on several occasions. Then he was appointed commander of the 1st Regiment of the 1st Route Army of the Northern Punitive Expeditionary Forces in 1926 when he was but 22 years of age. In 1927 he went to Japan and attended the Tokyo Military Officers' College, specializing in artillery. In 1929, when he took a trip through Kolea and the Three Eastern Provinces, he was dismissed from the school by the then Japanese War Minister on suspicion of being engaged in political activities.
Upon return to China, Mr. Sun was appointed commander of the artillery corps in the 1st Division of the Model Army and shortly afterwards promoted commander of the 7th Regiment of the 2nd Division of the National Army and commander of the 1st Brigade of 1st Division of the National Guards.
During the Shanghai hostilities with the Japanese in 1932 he was a Commander of the 259th Brigade of the 6th Army and fought valiantly against the Japanese in the battles of Miaohangchen and Laitangchen. In recognition of his meritorious services, he was promoted Commander of 88th Division in 1933 and while the Division was stationed along the ShanghaiNanking Line, he was concurrently Garrison Commander of Soochow and Changchow and Associate Garrison Commander of Nanking.
In the winter of 1933, when the Fukien rebellion broke out, his Division was transferred to Fukien and after the suppression of the rebellion, he joined the Government's 5th general campaign against the Communists in Kiangsi and succeeded in capturing many Red strongholds.