 During the 1930s and 1940s, Yang commanded the 344th Brigade of the 115th Division; the 1st Column of the Field Army of the Shanxi-Hebei-Shandong-Henan Military Area; and the 2nd and 19th Army Groups of the Northern China Military District.During the Second Sino-Japanese War, Yang studied at the Counter-Japanese University in 1937.In the late 1938 in southern Hebei, the 343rd Brigade joined Yang Yong's 68th Regiment to form the a unit known to the KMT as the Second Column of the Eighth Route Army, under the command of Yang Dezhi, with Yang Yong as his deputy and Su Zhenhua as political commissar.